WALD, Circuit Judge:
Following a jury trial on February 1-4, 1982, appellant, Claude L. Blackwell, was convicted of violating 18 U.S.C. app. § 1202(a)(1) (possession of a firearm by a convicted felon) and 22 D.C.Code § 3204 (carrying a pistol without a license). Blackwell was subsequently sentenced to a prison term of two to six years on the D.C.Code offense and a concurrent term not to exceed two years on the federal offense. On this appeal, Blackwell challenges the validity of his conviction on two grounds: (1) that four photographs showing Blackwell holding a gun were admitted into evidence at his trial in violation of Federal Rules of Evidence 901(a), 402, 403, and 404; and (2) that his sixth amendment right to have a witness testify on his behalf was violated by the prosecutor’s and the trial judge’s warnings to a defense witness that she could be prosecuted for perjury and lose the benefit of her plea bargain if she gave certain testimony. On the evidentiary issue, we hold that the trial court did not commit prejudicial error when it admitted the photographs in question into evidence. On the sixth amendment issue, we hold that the perjury warnings were proper. The warnings to the witness that her plea agreement might be revoked, however, reflected a misunderstanding of Rule 11 of the Federal Rules of Criminal Procedure and may have dissuaded Blackwell from presenting a witness in his defense. Nevertheless, we affirm the conviction because counsel failed to object to those remarks as inaccurate at trial, and they do not constitute plain error so as to be noticeable on appeal.
I. Background
On September 10,1981, Washington, D.C. police executed a search warrant at the Pitts Hotel, in a room rented by appellant’s common-law wife, Lillie T. Robinson. Both Robinson and appellant, Claude L. Blackwell, were present in the room when the search occurred. During their search, the police seized two guns hidden in the room, a .357 magnum Dan Wesson revolver and a .38 Smith & Wesson revolver; a brown canvas bag containing both live and spent .357 and .38 ammunition, weapon cleaning and breakdown tools, a Smith & Wesson box bearing the same serial number as that of the seized .38 revolver, Blackwell’s birth certificate, and a pawnbroker’s certificate with Blackwell’s name and address on it; marijuana; and four color photographs of Blackwell with a revolver similar to the .357 magnum discovered during the search.
Blackwell was subsequently charged with violating 18 U.S.C. app. § 1202(a)(1) (possession of a firearm by a convicted felon),1 21 U.S.C. § 844 (possession of marijuana),2 and 22 D.C.Code § 3204 (carrying a pistol without a license).3 Robinson was charged [1328]*1328with violating 21 U.S.C. § 844 and 22 D.C. Code § 3204.
On February 1, 1982, the district court accepted a plea agreement by which Robinson pled guilty to the marijuana possession charge in return for the dismissal of the gun possession charge. On the same day Blackwell proceeded to trial on the two weapons charges, the government having dismissed the marijuana possession charge.
At trial, the government introduced into evidence all the weaponry seized during the September 1981 search and several black and white photographs of Robinson’s hotel room taken during the search, which showed the two revolvers and their places of discovery, the brown canvas bag, and parts of the hotel room in the background. Over Blackwell’s objection, it also introduced the four color photographs of Blackwell discovered during the search.
The defense presented two witnesses: Eleazar Williams, Jr., a friend of Robinson’s, and Blackwell himself. Williams testified that on September 9, 1981, Robinson had accompanied him to a gun shop in Virginia, where he bought a .38 revolver and some ammunition.. He then used the .38, as well as his own .357 magnum revolver, for target practice. On their way home, Williams stated, his truck broke down. He left Robinson in charge of the truck and guns and went in search of a friend to help him repair the truck. When he returned several hours later, he discovered that Robinson had left, taking the guns with her. Williams also testified that the guns seized in the search at Robinson’s hotel room the next day were his.
Blackwell then took the stand, testifying that he did not live at Robinson’s hotel room, but visited there about three times a week. He denied ever seeing the two revolvers before the police discovered them on September 10, 1981. He also stated that the brown canvas bag belonged to Robinson; that his birth certificate and the pawnbroker’s ticket were on a nightstand in the room, not inside the bag; and that the four color photographs, introduced by the government were taken at another hotel in 1977.
Blackwell had also planned to call Robinson as a defense witness at his trial. Her testimony, Blackwell’s attorney later proffered, would have corroborated the testimony of Williams that Robinson, not Blackwell, had brought the guns to the hotel room. In addition, Robinson would have testified that Blackwell did not know of the presence of the guns in the room. Defense counsel first indicated to the trial court that he was going to subpoena Robinson to testify on behalf of Blackwell immediately after she entered her plea of guilty and before trial began. In response to this announcement, the prosecutor stated that he believed Robinson had a fifth amendment privilege not to testify because the charges against her were still pending. Robinson’s attorney agreed, telling the court that he had advised her to invoke her fifth amendment privilege against self-incrimination arid would like an opportunity to speak with her further on the subject.
On the second day of the trial, Robinson’s attorney informed the court that, against his advice, Robinson had decided to waive her fifth amendment privilege. The prosecutor then asked permission to inquire into the voluntariness of Robinson’s intended waiver, pointing out that there was a “close relationship” between Blackwell and Robinson and a “very substantial” question of perjury. The trial judge inquired of Blackwell’s attorney whether Robinson was going to claim that the two guns were hers; he replied that she was not going to make that claim. The judge then questioned Robinson under oath, advising her that she still retained a fifth amendment privilege because [1329]*1329she had not yet been sentenced and the gun possession charge was therefore still pending against her. The judge also told Robinson that if she testified falsely she would be subject to a charge of perjury. Robinson replied that she still wanted to take the stand and testify.
The court then gave the prosecutor permission to examine Robinson. He questioned her regarding her relationship with Blackwell; whether and when she and Blackwell discussed the possibility of her testifying on his behalf as well as the circumstances and the content of those discussions; why she wanted to testify; and if and why she wanted to waive her privilege against self-incrimination. His final question was, “[D]o you intend to claim possession of these weapons?” Although Robinson answered “No,” the court sustained Blackwell’s objection to the question, commenting that “if she were going to testify that the guns were hers, she would lay herself open to the case not being dismissed against her.” Tr. at 133.
Later in the trial, the defense called Williams to testify. The prosecutor objected, requesting a proffer of his testimony. After Blackwell’s attorney described what Williams’ testimony would be, the judge commented that she had not understood that Robinson was going to testify that she had possession of the weapons. The judge was disturbed that Robinson would be in the “incriminating situation of bringing the guns into the District of Columbia herself,” Tr. at 226, and remarked that if she testified as counsel had proffered, “[w]e obviously couldn’t allow [the weapons charge] to be dismissed.” Tr. at 228.
Apparently concerned that Robinson still did not understand that merely possessing, rather than owning, the guns would open her up to the gun possession charge, the court then questioned Robinson under oath once again, telling her that if she testified to possession of the weapons in the District of Columbia, she could be found guilty of the gun charge. Robinson replied that the guns were not hers and that she understood that just possessing them would make her liable for a gun possession charge. After this discourse, Blackwell’s attorney stated to the court Blackwell’s concern that if Robinson testified she would be prosecuted. The court replied, “She will. There is no doubt about it.” Tr. at 263.
Immediately after the trial judge made these comments, Blackwell took the stand to acknowledge his understanding that Robinson, should she testify, might be prosecuted on the original indictment for possession of a pistol without a license and could also be prosecuted under Virginia law for transporting weapons into the District of Columbia. As a result, Blackwell stated, he would withdraw the subpoena that had been issued to Robinson.
On February 4, 1982, Blackwell was convicted of both the charged offenses.
II. Analysis
A. The Evidentiary Issue
Blackwell argues on this appeal that the trial court’s admission of four photographs showing him holding a gun was a clear abuse of discretion because the photographs were unauthenticated and irrelevant. He urges that their admission therefore violated Federal Rules of Evidence 901(a), 402, 403, and 404. In order to authenticate the photographs properly, he contends, the government needed to identify conclusively the place and time the photographs were taken and also to prove that the weapon in the photographs was the same gun seized when he was arrested on September 10, 1981. Because the photographs were not so authenticated, Blackwell concludes, they were irrelevant to the case and inadmissible under the rules of evidence.
1. Authentication
As a general rule, tangible evidence such as photographs must be properly identified or authenticated before being admitted into evidence at trial. Fed.R.Evid. [1330]*1330901(a);4 Richardson v. Gregory, 281 F.2d 626, 630 (D.C.Cir.1960); Mikus v. United States, 433 F.2d 719 (2d Cir.1970); United States v. Hobbs, 403 F.2d 977, 978-79 (6th Cir.1968). Authentication and identification are specialized aspects of relevancy that are necessary conditions precedent to admissibility. 5 J. Weinstein and M. Berger, Weinstein’s Evidence |901(a)[02] at 901-18 (1978); 11 J. Moore and H. Bendix, Moore’s Federal Practice § 901.01[3.-l]-(a) at IX-7 (2d ed. 1982). Rule 901(a) only requires that the proponent of documentary evidence make a showing sufficient to permit a reasonable juror to find that the evidence is what its proponent claims. United States v. Sutton, 426 F.2d 1202, 1207 (D.C.Cir.1969).
The sufficiency of a showing of a document’s authenticity rests within the sound discretion of the trial judge. Id. at 1207; Jackson v. United States, 395 F.2d 615, 619 (D.C.Cir.1968); Richardson v. Gregory, 281 F.2d at 630. The trial court’s determination regarding admissibility will not be overturned absent a clear abuse of discretion.. Id.; United States v. Smith, 490 F.2d 789, 794 (D.C.Cir.1974) (per curiam).
The record in this case indicates that the following actions were taken regarding the showing of authenticity required by Rule 901(a). On the first day of trial, counsel for Blackwell alerted the trial judge that he planned to object to the admission of the photographs on the grounds that the government could not prove that the gun shown in the photographs was the same gun seized during the search in September 1981, that the room in the photographs was the same room as the one in which the search was made, or that the pictures were taken at a time relevant to the charged offenses. The admission of the photographs, Blackwell’s attorney argued, would therefore be irrelevant and immaterial to any issue in the case and also highly prejudicial to his client’s defense.
In response to this objection, the prosecutor proffered that there would be testimony forthcoming that the photographs showed Blackwell holding a gun that looked exactly like one of the seized weapons, in a room that looked exactly like Robinson’s hotel room. The judge thereupon decided that the government would be allowed to introduce the photographs.
The prosecutor did so through his first witness, a police officer who had participated in the search of Robinson’s hotel room. The officer, Detective Hampton, testified that the man shown in the photographs was the defendant, Blackwell. She also testified that the room depicted in the photographs looked exactly like the room she had searched in September 1981, pointing to such details as the similarities in the layout of the room in the Pitts Hotel and that shown in the pictures and in the appearance and positioning of the room’s chair, nightstand, air conditioner, bed, and draperies. In addition, Hampton testified that the gun in the photographs appeared to be identical to the gun seized during the search. When asked to detail the similarities, she testified:
The color, the black steel and the brown grips; in the end of the butt of the gun there’s a hole that’s reflected in the picture; the red inlay or red sights that are marked; the length of the barrel appears to be the same; the cylinder looks the same.
The rod that ejects the shells, the frame around the rod is built the same in this weapon as it is in the one in the picture.
Tr. at 118.
The goyernment also called a firearms examiner with the Washington, D.C. Metropolitan Police Department to testify regarding two of the photographs. He stated that these photographs showed a catalogue put out by the Dan Wesson Company. This catalogue, known as the Dan Wesson Pistol [1331]*1331Pack, described the .38 special and .357 magnum revolvers, the same two weapons found by the police at the Pitts Hotel. In addition, the government introduced several black and white photographs taken during the September 1981 search of Robinson’s room. These photographs were available to the jury so that it could compare such details as the appearance of the gun and the hotel room in them with the same details in the four color photographs.
After the introduction of this, evidence, a reasonable juror could have concluded that these were photographs of Blackwell, that they showed him with the same gun as one seized during the search, and that the photographs were taken at the Pitts Hotel.5 The government did not, however, present sufficient evidence to establish with any degree of certainty when the photographs were taken. Proper authentication requires not only that the government identify the scene depicted in the photographs, but also their coordinates in time and place. See United States v. Stearns, 550 F.2d 1167, 1171 (9th Cir.1977). Although the prosecutor did ask Detective Hampton if she knew when the pictures were taken or when Robinson moved into the Pitts Hotel, she was unable to answer either question. The government made no other attempt during its case-in-chief to pinpoint the time when the photographs might have been taken with any degree of certainty.6
Fortunately for the government, Blackwell himself provided some information on the relevant time period when he took the stand to testify near the end of trial. Blackwell stated that Robinson had moved into the Pitts Hotel in June of 1981. Based on the marked similarities between the room depicted in the four photographs in question here and the room depicted in the black and white photographs taken during the search of Robinson’s room, the jury could reasonably have concluded that the four color photographs had been taken at the Pitts Hotel sometime between June and September 1981. As a result, even if the photographs were not fully authenticated by the prosecution and their admission into evidence premature, any error was cured by the testimony of the defendant before the close' of the trial. A new trial is therefore not required on this ground.7
[1332]*13322. Relevance
In addition to being properly authenticated, the photographs must also La relevant to some matter at issue in the trial. United States v. Hurt, 476 F.2d 1164, 1170 (D.C.Cir. 1973) (per curiam); United States v. Hobson, 519 F.2d 765, 776 (9th Cir.), cert. denied, 423 U.S. 931, 96 S.Ct. 283, 46 L.Ed.2d 261 (1975). The test for relevance set out by Rule 401 refers to evidence “having any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.” The photographs in question here were clearly relevant to the prosecution’s contention that Blackwell had a .38 and a .357 revolver in his possession at the Pitts Hotel. Certainly, photographs showing the defendant holding a gun similar to one seized after his arrest in a room nearly identical to the room in which he was arrested have the tendency to make it more likely that the seized guns were in his possession at the time of their discovery.
Relevant evidence may be inadmissible under Rules 4038 and 404,9 however, if its probative value is outweighed by its inflammatory, prejudicial, or misleading nature or if it has been introduced solely to show the defendant’s propensity to commit the crime with which he has been charged. See United States v. Smith, 490 F.2d at 794; United States v. Hurt, 476 F.2d at 1170; Harried v. United States, 389 F.2d 281, 287 (D.C.Cir.1967). The probative value of these photographs would have been extremely high if it had been conclusively proven that the gun and room in the photographs were identical to the seized gun and the room at the Pitts Hotel and that the photographs were taken a short time before Blackwell’s arrest. This, of course, was not the case. As a result, the probative value of the" photographs is diminished, even though the gun and the room in the photographs closely resemble the seized gun and the Pitts room. In addition, the defendant may have been prejudiced by the admission of the photographs. One of the charges against Blackwell concerned possession of a firearm by a convicted felon. The photographs may have led the jury to believe that even if Blackwell had not possessed the guns found at the Pitts Hotel he had had some guns in his possession since his felony conviction. There is also some likelihood that the jury, after viewing these photographs, may have been prejudiced by Blackwell’s stance in one of them (holding a gun in firing position) and by his apparent ease and familiarity in the presence of weapons.10
In striking a balance, the trial court did not err in finding that the dangers associated with admitting the photographs [1333]*1333did not outweigh their probative value.11 Even though it was not conclusively proven that the room shown in the photographs was the Pitts Hotel room or that the gun seized was the same gun appearing in the photographs, those photographs did make it significantly more likely that they were the same room and the same gun and that, as a result, Blackwell was guilty of the charged crime of possession. In sum, the district court did not abuse its discretion when it admitted the photographs into evidence.
B. The Sixth Amendment Issue
The Sixth Amendment preserves the right to the defendant “to have compulsory process for obtaining witnesses in his favor.” Washington v. Texas, 388 U.S. 14, 19, 87 S.Ct. 1920, 1923, 18 L.Ed.2d 1019 (1967), clearly established that a party’s right to present his own witnesses in establishing a defense is a fundamental component of due process:
The right to offer the testimony of witnesses, and to compel their attendance, if necessary, is in plain terms the right to present a defense, the right to present the defendant’s version of the facts as well as the prosecution’s to the jury so it may decide where the truth lies. Just as an accused has the right to confront the prosecution’s witnesses for the purpose of challenging their testimony, he has the right to present his own witnesses to establish a defense. This right is a fundamental element of due process of law.
See also Chambers v. Mississippi, 410 U.S. 284, 302, 93 S.Ct. 1038, 1049, 35 L.Ed.2d 297 (1973) (“[f]ew rights are more fundamental than that of an accused to present witnesses in his own defense”).
Blackwell argues that he was unconstitutionally denied his right to obtain witnesses in his favor when the combined actions of the trial judge and the prosecutor forced him to abandon his plan to call Robinson as a defense witness. According to Blackwell, Robinson was prepared to testify that she had transported the two guns from Virginia to" the District of Columbia, that the guns were in her possession, not Blackwell’s, and that Blackwell knew nothing about them. When the judge and the prosecutor told Robinson she might then be prosecuted for perjury and for possession and that her plea bargain would be repudiated if she so testified, however, Blackwell was forced, he contends, to decline to call her as a defense witness.
The government argues that the actions of the trial judge and the prosecutor were designed merely to protect Robinson’s fifth amendment privilege against self-incrimination. There is no conviction after a plea or verdict of guilty, the government contends, until the court enters a judgment and imposes a sentence. Because the trial court had not yet sentenced Robinson, its argument runs, she remained in danger of incriminating herself on the gun charge, which was to be dismissed only when she was sentenced for possession of marijuana. The trial court and prosecutor were genuinely concerned, the government suggests, that Robinson did not truly understand that there was no difference between temporary possession and legal ownership of the guns for the purposes of opening herself up to prosecution. In addition, the government points out, the efforts of the trial court and the prosecutor did not intimidate Robinson since at no time did she ever refuse to testify.
Various types of governmental and judicial interference have been found to deprive the criminal defendant of the right to present his own witnesses to establish a defense. See, e.g., Webb v. Texas, 409 U.S. 95, 93 S.Ct. 351, 34 L.Ed.2d 330 (1972) (per curiam) (defense witness effectively driven off witness stand by remarks of trial judge regarding the penalties for perjury); Unit[1334]*1334ed States v. Smith, 478 F.2d 976 (D.C.Cir. 1973) (defense witness told by prosecutor that if he testified as indicated by other testimony he could or would be prosecuted for carrying a concealed weapon, obstructing justice, and as an accessory to murder); United States v. MacCloskey, 682 F.2d 468 (4th Cir.1982) (U.S. Attorney telephoned defendant’s girlfriend’s attorney to advise him to remind his client that if she testified at trial she could be reindicted on dropped charges); United States v. Goodwin, 625 F.2d 693 (5th Cir.1980) (defense witnesses intimidated by threats of prison officials conditioned upon whether the witnesses testified at trial); United States v. Hammond, 598 F.2d 1008 (5th Cir.1979) (defense witness threatened by FBI agent with retaliation in other cases pending against him); United States v. Henricksen, 564 F.2d 197 (5th Cir.1977) (per curiam) (defense witness intimidated by terms of his plea bargain in another case); United States v. Thomas, 488 F.2d 334 (6th Cir.1973) (per curiam) (defense witness told by secret service agent during recess of trial that he would be prosecuted for a felony if he testified); Berg v. Morris, 483 F.Supp. 179 (E.D.Cal.1980) (trial court coerced witness into giving inculpatory evidence by twice warning him that his probation would be revoked and perjury charges filed if the truth were not told). There are two alleged sources of judicial and prosecutorial misconduct in this case: (1) the warnings of the trial judge and prosecutor that Robinson’s testimony could open her up to charges of perjury; and (2) their statements that if Robinson testified as had been proffered the gun charge scheduled to be dismissed as part of her plea bargain would not be dismissed. We find that the warnings concerning perjury were proper, and that the judge’s and the prosecutor’s comments telling Robinson that the gun charge could be reinstated, while reflecting an erroneous construction of Fed.R.Crim.P. 11, did not constitute “plain error” under the circumstances of this case so as to justify reversal of Blackwell’s conviction.
1. Perjury Warnings
The constitutional right of a . criminal defendant to call witnesses in his defense mandates that they be free to testify without fear of governmental retaliation. It is not improper per se for a trial court judge or prosecuting attorney to advise prospective witnesses of the penalties for testifying falsely. See, e.g., United States v. Simmons, 670 F.2d 365 (D.C.Cir.1982) (per curiam). But warnings concerning the dangers of perjury cannot be emphasized to the point where they threaten and intimidate the witness into refusing to testify. See Webb v. Texas, 409 U.S. 95, 93 S.Ct. 351, 34 L.Ed.2d 330; United States v. Harlin, 539 F.2d 679 (9th Cir.), cert. denied, 429 U.S. 942, 97 S.Ct. 362, 50 L.Ed.2d 313 (1976); United States v. Morrison, 535 F.2d 223 (3d Cir.1976); Berg v. Morris, 483 F.Supp. 179.
The prosecutor and trial judge in this case each warned Robinson of the consequences of perjury on Only one occasion. When the prosecutor first heard, on the second day of trial, that Robinson had decided to waive her privilege against self-incrimination and testify as a defense witness, he asked permission of the court to inquire into the voluntariness of her intended waiver, citing the “close relationship” between Blackwell and Robinson and pointing out that a “very substantial question of perjury” was involved. The trial judge then questioned Robinson under oath, stating:
there are always actions of perjury meaning that if you lie under oath that you can be sent away on a new charge.
Do you understand that?
THE WITNESS: Yes.
THE COURT: So it is important for everybody to tell the truth. I just want you to understand what the situation is. All right?
THE WITNESS: Thank you.
THE COURT: Do you still wish to take the stand and testify?
THE WITNESS: Yes.
Tr. at 130. The record reveals no other warnings to Robinson regarding the dangers of committing perjury.
[1335]*1335The conduct of the judge and the prosecutor just recounted does not begin to approach the level of misconduct described in Webb v. Texas or United States v. Morrison. In Webb, for example, the Supreme Court reversed a conviction for burglary when a trial judge gratuitously and at great length warned a witness of the dire consequences of committing perjury. The trial judge had told the witness:
If you take the witness stand and lie under oath, the Court will personally see that your case goes to the grand jury and you will be indicted for perjury and the liklihood [sic] is that you would get convicted of perjury and that it would be stacked onto what you have already got, so that is the matter you have got to make up your mind on. If you get on the witness stand and lie, it is probably going to mean several years and at least more time that you are going to have to serve. It will also be held against you in the penitentiary when you’re up for parole and the Court wants you to thoroughly understand the chances you’re taking by getting on that witness stand under oath. You may tell the truth and if you do, that is all right, but if you lie you can get into real trouble. The court wants you to know that. You don’t owe anybody anything to testify and it must be done freely and voluntarily and with the thorough understanding that you know the hazard you are taking.
409 U.S. at 96, 93 S.Ct. at 352. The Supreme Court held that these “threatening remarks” had effectively driven the witness off the stand, thereby depriving the defendant of due process of law. Id. at 98, 93 S.Ct. at 353.
In Morrison, the prosecutor sent at least three messages to a potential defense witness through her attorney warning her that, if she testified, she was liable to prosecution, that her testimony would be used as evidence against her, and that it would be possible to bring federal perjury charges against her. In addition, he subpoenaed the witness and had her brought to his office for an intimidating personal interview, telling her during the interview that
if she testified falsely ... she could subject herself to a perjury charge, and I told her that even though the charges were dismissed against her as an adult on the dope charge itself, that if she testified falsely she was now an adult over 18, and if we could prove it, and she was testifying falsely on behalf of [the defendant] thinking to get her to lie to exculpate himself and get off the hook, she could be prosecuted for perjury, and she should know that.
535 F.2d at 226. As a result of these activities on the part of the prosecutor, the court held that the defendant’s constitutional right to have this particular witness’ freely given testimony had been infringed. Id. at 228.
Rather, this case falls within this circuit’s rule requiring more than a mere warning regarding the dangers of perjury before reversal of a criminal conviction is warranted. United States v. Simmons, 670 F.2d 365. In Simmons, this court remanded a case to the district court for a full hearing on the defendant’s charge of prosecutorial misconduct; at the same time, however, we stated that “[i]t is hardly a threat for a prosecutor to advise a potential witness, who is telling two stories with respect to a defendant’s criminal involvement, that he might be prosecuted for perjury if he testifies falsely.”12 Id. at 371. See also United [1336]*1336States v. Harlin, 539 F.2d 679 (trial court did not deprive defendant of due process when it stated in his presence to counsel representing a codefendant that “I assume you have advised her of the penalties of perjury .. . and that if it appears that a defendant is lying, the Court can take that into account, too”).
The trial judge and prosecutor in this case stayed well within acceptable limits in their warnings to Robinson regarding the potential dangers of committing perjury if she testified. Their conduct in this regard gave rise to no legitimate constitutional complaint.
2. Warnings on Reinstatement of the Dismissed Charge
a. Violation of Rule 11
During trial, the judge repeatedly stated and the prosecutor suggested on one occasion that the gun charge which was to be dropped as part of Robinson’s plea bargain would be reinstated if she testified in Blackwell’s defense that she, not Blackwell, had brought the guns into the hotel room. These warnings, in our view, reflected a serious misunderstanding of Fed.R.Crim.P. 11 on the part of the trial judge.
On the first day of Blackwell’s trial, Robinson pled guilty to possession of marijuana in return for the dismissal of a gun possession charge. Immediately after the trial judge accepted the plea, Blackwell’s attorney indicated that he was going to call Robinson to testify in Blackwell’s behalf. At that time, the prosecutor stated that Robinson had a fifth amendment privilege not to testify because “the charges are still pending,” implying that she could still be prosecuted on the charge scheduled to be dismissed in the plea. Blackwell’s counsel did not object to the accuracy of the prosecution’s remarks on the status ox the gun charge.
The next day Robinson’s attorney informed the court that Robinson planned to waive her fifth amendment privilege and testify for the defense. The judge then questioned Robinson, informing her that I just wanted to be sure that you understand that, first of all, you have an absolute right not to testify in this case, as you know; you have a right to testify.
You have been subpoenaed and you have a Fifth Amendment right, because you haven’t been sentenced yet and you still have your charges hanging over your head.
The only understanding was that they would be dismissed at the time of sentence.
Now, it would work against you, as I am sure you understand....
Tr. at 129-30 (emphasis added).
The judge reiterated this point several times during Blackwell’s trial. When the prosecutor asked Robinson, who was called to the stand at the request of the judge, whether she would claim possession of the weapons if she testified, the trial judge sustained defense counsel’s objection to the question, commenting that “if she were going to testify that the guns were hers, she would lay herself open to the case not being dismissed against her.” Tr. at 133. At another point in the trial, the judge indicated her concern that Robinson would be in the “incriminating situation of bringing the guns into the District of Columbia herself,” Tr. at 226, and remarked that if she testified as defense counsel proffered, “[w]e obviously couldn’t allow [the weapons charge] to be dismissed.” Tr. at 228. The judge also informed Robinson personally that if she testified that she possessed the guns in the District of Columbia, she “could be found guilty of the gun charges.” Tr. at 261. At no time did Blackwell’s counsel indicate disagreement with or object to the judge’s warnings concerning the gun charge.
Near the end of the trial, however, Blackwell’s attorney mentioned to the court Blackwell’s concern that if Robinson testified she would be prosecuted. The court answered, “She will. There is no doubt about it.” Tr. at 263. Immediately there[1337]*1337after, Blackwell withdrew his subpoena for Robinson, stating under oath that he was doing so because if she testified she could still be prosecuted on the original gun charge and because it was at least conceivable that she might also invite prosecution for violations of Virginia law for transporting weapons into the District of Columbia.
Our reading of Fed.R.Crim.P. 11 persuades us that both the judge and the prosecutor were bound by the plea agreement accepted by the court on the first day of the trial. Neither had the power to renege on the agreement as to dismissal of the gun charge.13
As far as the prosecutor is concerned, it is no longer open to question that “when a plea rests in any significant degree on a promise or agreement of the prosecutor, so that it can be said to be part of the inducement or consideration, such promise must be fulfilled.” Santobello v. New York, 404 U.S. 257, 262, 92 S.Ct. 495, 499, 30 L.Ed.2d 427 (1971). As this court recently stated in United States v. Pardo, 636 F.2d 535, 543 (D.C.Cir.1980), “promises to dismiss charges as part of a plea agreement are binding on the Government.” As a result, “a witness may not be exposed to prosecution on [the dismissed] charges.” Id. Thus, in this case the government could not have refused to keep its promise to dismiss the gun charge simply because Robinson subsequently testified in Blackwell’s defense.14 Consequently, it was misleading for the prosecutor even to suggest that this might occur.15
[1338]*1338Robinson’s plea to the drug charge was expressly based on the government’s promise to dismiss the gun charge at the time of sentencing. Once she accepted that plea on the record, we believe that the trial judge was also without authority to vacate the plea and order reinstatement of the gun charge. Although, as pointed out in Santobello, 404 U.S. at 262, 92 S.Ct. at 499, there is “no absolute right to have a guilty plea accepted,” and “[a] court may reject a plea in exercise of sound judicial discretion,” once a judge has accepted a plea and bound the defendant to it, she cannot, except possibly for fraud, refuse to carry through on the bargain. Even if the trial judge at the time the plea was offered might have questioned Robinson about her intentions to testify in favor of Blackwell, and even if she might have refused to accept the plea if Robinson had indicated that she would so testify, once the plea was accepted the judge no longer had discretion to repudiate the agreement because of Robinson’s subsequent testimony.
We base this conclusion on the straightforward language of Fed.R.Crim.P. 11, which states that the judge shall indicate on the record at the time a plea is offered whether she will accept it, reject it, or defer the decision. See Rule 11(e)(2); 8 Moore’s Federal Practice K 11.05[2] at 11-90. In addition, Fed.R.Crim.P. 11(e)(3) makes it mandatory, if the trial judge accepts a plea agreement, that she tell the defendant that she will incorporate in the judgment and sentence the disposition provided for in the plea agreement. “This serves the purpose of informing the defendant immediately that the agreement will be implemented.”16 Fed.R.Crim.P. 11 advisory committee note, 1974 amendment (emphasis added).
There is no dispute that the trial judge here accepted the guilty plea and that its bargained-for predicate, the dismissal of the gun charge at the time of sentencing, was set out on the record and accepted by her as well. Indeed, the trial judge expressly warned Robinson when she accepted her plea that “in the event that you should want to withdraw this plea before the imposition of sentence, the Court would tell you that because we are ready to proceed to trial right now, you would not be permitted to do that either.” Transcript of plea at 3-4. The plea and the bargain were sealed at that point,17 and we know of no authority for the judge, short of evidence of fraud,18 to change her mind as to the wis[1339]*1339dom of the bargain and refuse to enforce it.19
Indeed, Rule ll’s requirement that the judge make a definite announcement of acceptance, rejection, or deferral of her decision about a plea bargain is indispensible to a criminal justice system so heavily dependent on plea bargaining. See Santobello v. New York, 404 U.S. at 260, 92 S.Ct. at 498 (plea bargaining is “an essential component of the administration of justice”). Pleas that bind only the defendant, or even the prosecutor and the defendant, but not the judge, would be unfair to the defendant and would dilute the incentive for defendants to plead at all. If compliance with the terms of a plea bargain were to be dependent on some implied but unannounced conditions of good behavior between the acceptance of the plea and the imposition of the sentence, the advantages to the defendant of pleading guilty would be substantially reduced. Rule 11 appears to speak unequivocally; if the plea is accepted, the judge does not announce any deferral of that acceptance, and the defendant adheres to the terms of the bargain, all parties to it are bound. Although the rule does permit deferral of the decision to accept or-reject the plea, usually for the purpose of viewing the presentence report, the mere postponement of the sentencing itself to a future date does not auc iorize the judge to remake or vacate the plea bargain for whatever reasons later seem appropriate to her.
The judge’s faithful observance of the requirements of Rule 11 is just as vital to the fairness and efficiency of the process as the prosecutor’s compliance. She has a primary duty under that rule to insure not only that the terms of the bargain are understood by the defendant but that they are adhered to by both sides, as well as by the court itself. That, we believe, is the purpose of Rule ll’s insistence that there be a public record of the terms of plea bargains.20
[1340]*1340In this case, perhaps inadvertently but nonetheless certainly, the trial judge misled both Robinson and Blackwell by stating that the gun charge to be dismissed as part of Robinson’s plea agreement could still be prosecuted. This information, moreover, had a definite potential for infringing Blackwell’s sixth amendment right to present witnesses in his own defense. Since counsel failed to raise the proper objection at trial to the warnings of reinstatement,21 however, we must now decide whether the error was evident enough and the resultant prejudice to Blackwell attributable to the warnings grave enough to constitute “plain error” requiring reversal of Blackwell’s conviction. Although the question is a close one, we conclude that the error was not plain, and therefore affirm the conviction.22
b. Plain Error
Fed.R.Crim.P. 52 recognizes three classes of errors, two explicitly and one implicitly: first, errors that do not prejudice the defendant are considered “harmless” and disregarded on appeal, whether or not objected to at trial; second, errors that may have been prejudicial and were objected to at trial are deemed “reversible”; and third, errors that are so fundamental a violation of the defendant’s rights that they require reversal regardless of the defendant’s failure to object to them at trial are termed “plain.” 3A C. Wright, Federal Practice and Procedure: Criminal 2d § 851 (1982). Rule 52(b) allows appellate courts to correct “[pjlain errors or defects affecting substantial rights” although they were not brought to the attention of the trial court. See United States v. Frady, 456 U.S. 152, 163, [1341]*1341102 S.Ct. 1584, 1592, 71 L.Ed.2d 816 (1982); United States v. Alston, 551 F.2d 315, 320-21 (D.C.Cir.1976); United States v. Williams, 463 F.2d 958, 962 (D.C.Cir.1972); United States v. McClain, 440 F.2d 241, 245 (D.C.Cir.1971).
Although a cursory reading of the rule would seem to require only that the unobjected-to error be a plain one (i.e., so obvious that the judge should have recognized it on her own) or that it affect substantial rights (i.e., that it not be harmless), the case law on which the rule rests requires much more. According to the Supreme Court’s latest pronouncement, the plain error rule is to be “used sparingly” and only “in those circumstances in which a miscarriage of justice would otherwise result.” United States v. Frady, 456 U.S. at 163 n. 14, 102 S.Ct. at 1592 n. 14. From that we surmise that neglected error must rise to a level far above that required to survive Rule 52(a)’s ban against reversals for harmless error.23
On the basis of a careful weighing of the factors discussed below, we find that the error in this case, while probably “reversible” if objected to at trial, does not rise to the level of error so “obvious and substantial” or so “serious and manifest,” 3A C. Wright, Federal Practice and Procedure: Criminal 2d § 856 at 336, that it affects the very integrity of the trial process, and requires reversal of Blackwell’s conviction. We do not find this to be a situation where a defendant is “convicted in a way inconsistent with the fairness and integrity of judicial proceedings, [and where] the courts should invoke the plain error rule in order to protect their own public reputation.” Id. at 341; United States v. Atkinson, 297 U.S. 157, 56 S.Ct. 391, 80 L.Ed. 555 (1936).
(1) The Substantiality of the Right Affected
Rule 52(a) mandates that errors at trial that do not affect substantial rights of the defendant are insufficient to reverse a criminal conviction on appeal. Although the Supreme Court has held that some constitutional rights are “so basic to a fair trial that their infraction can never be treated as harmless error ...,” Chapman v. California, 386 U.S. 18, 23, 87 S.Ct. 824, 827, 17 L.Ed.2d 705 (1967), and four circuits have held that intimidation of defense witnesses requires reversal without a showing of prejudice, see United States v. Hammond, 598 F.2d at 1013; United States v. Morrison, 535 F.2d at 228; United States v. Thomas, 488 F.2d at 336; Bray v. Peyton, 429 F.2d 500, 501 (4th Cir.1970) (per curiam); see also United States v. MacCloskey, 682 F.2d at 479; Berg v. Morris, 483 F.Supp. at 186-87, more recently the Court has stated that “interests protected by the Sixth Amendment look to the degree of prejudice incurred by a defendant as a result of governmental action or inaction.” United States v. Valenzueia-Bernal, - U.S. -, 102 S.Ct. 3440, 3448, 73 L.Ed.2d 1193 (1982).
On the basis of the trial record in this case, we cannot decide that it could have made no significant difference to the jury if Robinson had testified along the lines suggested in the proffer. See id. at 3447 (defendant must show testimony of deported witness “would have been both material and favorable to his defense”). Although the testimony of Williams, Blackwell’s only defense witness other than himself, paralleled the proffer for Robinson, the significance of Robinson’s nonappearance could not have been lost on the jury. Robinson was Blackwell’s common-law wife and the person in whose name the hotel room where the guns were found was rented. The fact that she did not take the stand to corroborate or supplement Williams’ testimony as to how the guns came to be found in the Pitts Hotel room or to testify whether Blackwell knew they were there could have been a fatal gap in his defense. Robinson was the only logical person other than Blackwell who might have known the circumstances of the guns’ presence in the [1342]*1342room and the extent of Blackwell’s knowledge of their presence. Indeed, Robinson allegedly told Blackwell’s attorney, who then informed the court, that “there was absolutely no way in the world Mr. Blackwell knew that those guns were in the apartment.” Tr. at 262. Robinson kept knowledge of her possession of the guns from Blackwell, his attorney stated, because she knew he had a prior record and because she did not want Blackwell to know she had been in Virginia with Williams.
Since the test for prejudice in cases of this type is whether the missing evidence might likely have substantially affected the outcome of the trial, see United States v. Bass, 535 F.2d 110 (D.C.Cir.1976); Rule 52(b), we assess the substantiality of the right affected as militating in favor of finding plain error in this case.
(2) The Novelty of the Legal Issue Alleged As Plain Error
As we have pointed out, the error in interpreting Rule 11 was one not previously ruled upon by this court. Indeed, none of the participants at trial — prosecutor, defense counsel, or trial judge — appears to have been aware it was an error. Thus, this is not the ease of an obvious error which went unobjected-to in the heat of trial.
A key reason for requiring that an error be objected to if it is to be noticed on appeal is so that a trial court will have a fair and prompt opportunity to cure or prevent the original error, or at least any recurrences. That principle is especially appropriate here, since the misinformation was conveyed on several occasions during trial; an objection the first time might have focused attention on the issue and allowed the judge to retract her warnings, thereby curing any potential harm to Blackwell. Also, if the defendant had objected, the prosecutor might possibly have been able to produce evidence to justify reinstatement of the charges under a fraud exception to Rule 11. If, as we discern the situation here, no objection was made because defense counsel labored under the same misapprehension abo.ut the judge’s power to reinstate the gun charge as the judge herself did, that too militates against labelling the error as one that implicates the “fairness and integrity of judicial proceedings” or represents a “miscarriage of justice.” We must be very confident before applying the plain error doctrine to issues of first impression in interpreting the Federal Rules of Criminal Procedure, unless the rule in question incorporates a well-established constitutional or legal principle. Since Rule 11 was designed to set up a new uniform structure for the acceptance of guilty pleas, where there had been none before, its correct interpretation and application may require some trial and error. In sum, the lack of prior precedent in the circuit and the novelty of the issue presented militate against calling the judge’s mistake plain error.
(3) The Defendant’s Failure to Preserve His Right
Finally, the clear causal connection between the misinformation conveyed by the judge’s and prosecutor’s remarks and the failure of Robinson to testify is weak; thus, we cannot be sure that the Rule 11 violation infringed Blackwell’s constitutional right. This concern tilts our decision against a finding of plain error in this case. As the government points out, Blackwell himself abandoned the right to call Robinson to the witness stand.
This circumstance serves to distinguish the case from the usual one in which the witness succumbs to intimidation by the trial judge or the prosecutor and refuses to testify. See, e.g., Webb v. Texas, 409 U.S. 95, 93 S.Ct. 351, 34 L.Ed.2d 330; United States v. Simmons, 670 F.2d 335; United States v. Smith, 478 F.2d 976; United States v. MacCloskey, 682 F.2d 468; United States v. Hammond, 598 F.2d 1008; United States v. Thomas, 488 F.2d 334; Berg v. Morris, 483 F.Supp. 179. While we would be reluctant to rule that the same constitutional protections that apply against prosecutorial and judicial acts that directly intimidate a defense witness have no application to acts that motivate a defendant to refuse to expose a particular witness to risk, especially one with whom he has an [1343]*1343intimate family relationship, the peculiar circumstances surrounding Robinson’s failure to be called to the stand make us reluctant to reverse the conviction because she did not testify.
We all recognize a potential for abuse if a defendant is allowed to forego calling a key witness solely on his assertion that he is protecting her welfare. It is always possible that the defendant is really refraining from calling a witness because the testimony might not be favorable to him or because the witness intended to raise the privilege on grounds other than the mistaken fear that the charges in a plea bargain could be reinstated. In this case, all we know is that the defendant took the stand immediately after the trial judge’s warnings to the witness and testified he would not call her, although he had previously intended to, because of the threat of renewed prosecution on the gun charge and of possible prosecution on a state gun charge. The witness, on the other hand, had only minutes before stated her continued intention to testify. In short, we have no way of knowing what would have actually happened if Blackwell had called Robinson as a defense witness. We have obvious concerns about allowing a defendant to decide for himself when legal risks to another person will suffice to permit him to waive his constitutional right to a defense witness and still assign it as plain error on appeal. Where, as here, the witness herself never refuses to testify, the nexus between the error and the loss of her testimony to the defendant is inevitably attenuated and the substantiality of the harm' attributable to the error less than “manifest.”24 While on balance, if it had been objected to at trial, we might have concluded that the misinformation constituted harmful and reversible error, under this scenario we cannot find that it meets the significantly higher standard required for plain error.
In sum, the error was “plain” to no one at trial and had not been ruled on previously by this court; it also involved the interpretation of a relatively recent federal rule, rather than a well-established constitutional or common law right. More important, however, is the lack of a direct nexus between the judge’s and prosecutor’s remarks and Blackwell’s loss of Robinson’s testimony. On balance, despite the violation of Rule 11 and the sixth amendment interest implicated, we find no plain error sufficient to require reversal of the conviction.
Affirmed.