[227]*227Mr. Justice Powell
delivered the opinion of the Court.
In a criminal trial, defense counsel sought to impeach the credibility of key prosecution witnesses by testimony of a defense investigator regarding statements previously obtained from- the witnesses by the investigator. The question presented here is whether in these circumstances a federal trial court may compel the defense to reveal the relevant portions of the investigator’s report for the prosecution’s use in cross-examining him. The United States Court of Appeals for the Ninth Circuit concluded that it cannot. 501 F. 2d 146. We granted certiorari, 419 U. S. 1120 (1975), and now reverse.
I
Respondent was tried and convicted on charges arising from an armed robbery of a federally insured bank. The only significant evidence linking him to the crime was the identification testimony of two witnesses, a bank teller and a salesman who was in the bank during the robbery.1 Respondent offered an alibi but, as the Court of Appeals recognized, 501 F. 2d, at 150, his strongest defense centered around attempts to discredit these eyewitnesses. Defense efforts to impeach them gave rise to the events that led to this decision.
In the course of preparing respondent’s defense, an investigator for the defense interviewed both witnesses and preserved the essence of those conversations in a written report. When the witnesses testified for the prosecution, respondent’s counsel relied on the report in conducting their cross-examination. Counsel asked the bank [228]*228teller whether he recalled having told the investigator that he had seen only the back of the man he identified as respondent. The witness replied that he did not remember making such a statement. He was allowed, despite defense counsel’s initial objection, to refresh his recollection by referring to a portion of the investigator’s report. The prosecutor also was allowed to see briefly the relevant portion of the report.2 The witness thereafter testified that although the report indicated that he told the investigator he had seen only respondent’s back, he in fact had seen more than that and continued to insist that respondent was the bank robber.
The other witness acknowledged on cross-examination that he too had spoken to the defense investigator. Respondent’s counsel twice inquired whether he told the investigator that “all blacks looked alike” to him, and in each instance the witness denied having made such a statement. The prosecution again sought inspection of the relevant portion of the investigator’s report, and respondent’s counsel again objected. The court declined to order disclosure at that time, but ruled that it would be required if the investigator testified as to the witnesses’ alleged statements from the witness stand.3 The [229]*229court further advised that it would examine the investigator’s report in camera and would excise all reference to matters not relevant to the precise statements at issue.
After the prosecution completed its case, respondent called the investigator as a defense witness. The court reiterated that a copy of the report, inspected and edited in camera, would have to be submitted to Government counsel at the completion of the investigator’s impeachment testimony. When respondent’s counsel stated that he did not intend to produce the report, the court ruled that the investigator would not be allowed to testify about his interviews with the witnesses.4
The Court of Appeals for the Ninth Circuit, while acknowledging that the trial court’s ruling constituted a “very limited and seemingly judicious restriction,” 501 F. 2d, at 151, nevertheless considered it reversible [230]*230error. Citing United States v. Wright, 160 U. S. App. D. C. 57, 68, 489 F. 2d 1181, 1192 (1973), the court found that the Fifth Amendment prohibited the disclosure condition imposed in this case. The court further held that Fed. Rule Crim. Proc. 16, while framed exclusively in terms of pretrial discovery, precluded prosecutorial discovery at trial as well. 501 F. 2d, at 157; accord, United States v. Wright, supra, at 66-67, 489 F. 2d, at 1190-1191. In each respect, we think the court erred.
II
The dual aim of our criminal justice system is “that guilt shall not escape or innocence suffer,” Berger v. United States, 295 U. S. 78, 88 (1935). To this end, we have placed our confidence in the adversary system, entrusting to it the primary responsibility for developing relevant facts on which a determination of guilt or innocence can be made. See United States v. Nixon, 418 U. S. 683, 709 (1974); Williams v. Florida, 399 U. S. 78, 82 (1970); Elkins v. United States, 364 U. S. 206, 234 (1960) (Frankfurter, J., dissenting).
While the adversary system depends primarily on the parties for the presentation and exploration of relevant facts, the judiciary is not limited to the role of a referee or supervisor. Its compulsory processes stand available to require the presentation of evidence in court or before a grand jury. United States v. Nixon, supra; Kastigar v. United States, 406 U. S. 441, 443-444 (1972) ; Murphy v. Waterfront Comm’n, 378 U. S. 52, 93-94 (1964) (White, J., concurring). As we recently observed in United States v. Nixon, supra, at 709:
“We have elected to employ an adversary system of criminal justice in which the parties contest all issues before a court of law. The need to develop all relevant facts in the adversary system is both [231]*231fundamental and comprehensive. The ends of criminal justice would be defeated if judgments were to be founded on a partial or speculative presentation of the facts. The very integrity of the judicial system and public confidence in the system depend on full disclosure of all the facts, within the framework of the rules of evidence. To ensure that justice is done, it is imperative to the function of courts that compulsory process be available for the production of evidence needed either by the prosecution or by the defense.”
Decisions of this Court repeatedly have recognized the federal judiciary’s inherent power to require the prosecution to produce the previously recorded statements of its witnesses so that the defense may get the full benefit of cross-examination and the truth-finding process may be enhanced. See, e. g., Jencks v. United States, 353 U. S. 657 (1957);5 Gordon v. United States, 344 U. S. 414 (1953); Goldman v. United States, 316 U. S. 129 (1942); Palermo v. United States,
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[227]*227Mr. Justice Powell
delivered the opinion of the Court.
In a criminal trial, defense counsel sought to impeach the credibility of key prosecution witnesses by testimony of a defense investigator regarding statements previously obtained from- the witnesses by the investigator. The question presented here is whether in these circumstances a federal trial court may compel the defense to reveal the relevant portions of the investigator’s report for the prosecution’s use in cross-examining him. The United States Court of Appeals for the Ninth Circuit concluded that it cannot. 501 F. 2d 146. We granted certiorari, 419 U. S. 1120 (1975), and now reverse.
I
Respondent was tried and convicted on charges arising from an armed robbery of a federally insured bank. The only significant evidence linking him to the crime was the identification testimony of two witnesses, a bank teller and a salesman who was in the bank during the robbery.1 Respondent offered an alibi but, as the Court of Appeals recognized, 501 F. 2d, at 150, his strongest defense centered around attempts to discredit these eyewitnesses. Defense efforts to impeach them gave rise to the events that led to this decision.
In the course of preparing respondent’s defense, an investigator for the defense interviewed both witnesses and preserved the essence of those conversations in a written report. When the witnesses testified for the prosecution, respondent’s counsel relied on the report in conducting their cross-examination. Counsel asked the bank [228]*228teller whether he recalled having told the investigator that he had seen only the back of the man he identified as respondent. The witness replied that he did not remember making such a statement. He was allowed, despite defense counsel’s initial objection, to refresh his recollection by referring to a portion of the investigator’s report. The prosecutor also was allowed to see briefly the relevant portion of the report.2 The witness thereafter testified that although the report indicated that he told the investigator he had seen only respondent’s back, he in fact had seen more than that and continued to insist that respondent was the bank robber.
The other witness acknowledged on cross-examination that he too had spoken to the defense investigator. Respondent’s counsel twice inquired whether he told the investigator that “all blacks looked alike” to him, and in each instance the witness denied having made such a statement. The prosecution again sought inspection of the relevant portion of the investigator’s report, and respondent’s counsel again objected. The court declined to order disclosure at that time, but ruled that it would be required if the investigator testified as to the witnesses’ alleged statements from the witness stand.3 The [229]*229court further advised that it would examine the investigator’s report in camera and would excise all reference to matters not relevant to the precise statements at issue.
After the prosecution completed its case, respondent called the investigator as a defense witness. The court reiterated that a copy of the report, inspected and edited in camera, would have to be submitted to Government counsel at the completion of the investigator’s impeachment testimony. When respondent’s counsel stated that he did not intend to produce the report, the court ruled that the investigator would not be allowed to testify about his interviews with the witnesses.4
The Court of Appeals for the Ninth Circuit, while acknowledging that the trial court’s ruling constituted a “very limited and seemingly judicious restriction,” 501 F. 2d, at 151, nevertheless considered it reversible [230]*230error. Citing United States v. Wright, 160 U. S. App. D. C. 57, 68, 489 F. 2d 1181, 1192 (1973), the court found that the Fifth Amendment prohibited the disclosure condition imposed in this case. The court further held that Fed. Rule Crim. Proc. 16, while framed exclusively in terms of pretrial discovery, precluded prosecutorial discovery at trial as well. 501 F. 2d, at 157; accord, United States v. Wright, supra, at 66-67, 489 F. 2d, at 1190-1191. In each respect, we think the court erred.
II
The dual aim of our criminal justice system is “that guilt shall not escape or innocence suffer,” Berger v. United States, 295 U. S. 78, 88 (1935). To this end, we have placed our confidence in the adversary system, entrusting to it the primary responsibility for developing relevant facts on which a determination of guilt or innocence can be made. See United States v. Nixon, 418 U. S. 683, 709 (1974); Williams v. Florida, 399 U. S. 78, 82 (1970); Elkins v. United States, 364 U. S. 206, 234 (1960) (Frankfurter, J., dissenting).
While the adversary system depends primarily on the parties for the presentation and exploration of relevant facts, the judiciary is not limited to the role of a referee or supervisor. Its compulsory processes stand available to require the presentation of evidence in court or before a grand jury. United States v. Nixon, supra; Kastigar v. United States, 406 U. S. 441, 443-444 (1972) ; Murphy v. Waterfront Comm’n, 378 U. S. 52, 93-94 (1964) (White, J., concurring). As we recently observed in United States v. Nixon, supra, at 709:
“We have elected to employ an adversary system of criminal justice in which the parties contest all issues before a court of law. The need to develop all relevant facts in the adversary system is both [231]*231fundamental and comprehensive. The ends of criminal justice would be defeated if judgments were to be founded on a partial or speculative presentation of the facts. The very integrity of the judicial system and public confidence in the system depend on full disclosure of all the facts, within the framework of the rules of evidence. To ensure that justice is done, it is imperative to the function of courts that compulsory process be available for the production of evidence needed either by the prosecution or by the defense.”
Decisions of this Court repeatedly have recognized the federal judiciary’s inherent power to require the prosecution to produce the previously recorded statements of its witnesses so that the defense may get the full benefit of cross-examination and the truth-finding process may be enhanced. See, e. g., Jencks v. United States, 353 U. S. 657 (1957);5 Gordon v. United States, 344 U. S. 414 (1953); Goldman v. United States, 316 U. S. 129 (1942); Palermo v. United States, 360 U. S. 343, 361 (1959) (Brennan, J., concurring in result). At issue here is whether, in a proper case, the prosecution can call upon that same power for production of witness statements that facilitate “full disclosure of all the [relevant] facts.” United States v. Nixon, supra, at 709.
In this case, the defense proposed to call its investigator to impeach the identification testimony of the prosecution’s eyewitnesses. It was evident from cross-examination that the investigator would testify that each witness’ recollection of the appearance of the individual identified as respondent was considerably less clear at [232]*232an earlier time than it was at trial. It also appeared that the investigator and one witness differed even as to what the witness told him during the interview. The investigator’s contemporaneous report might provide critical insight into the issues of credibility that the investigator’s testimony would raise. It could assist the jury in determining the extent to which the investigator’s testimony actually discredited the prosecution’s witnesses. If, for example, the report failed to mention the purported statement of one witness that “all blacks looked alike,” the jury might disregard the investigator’s version altogether. On the other hand, if this statement appeared in the contemporaneously recorded report, it would tend strongly to corroborate the investigator’s version of the interview and to diminish substantially the reliability of that witness’ identification.6
It was therefore apparent to the trial judge that the investigator’s report was highly relevant to the critical issue of credibility. In this context, production of the report might substantially enhance “the search for truth,” Williams v. Florida, 399 U. S., at 82. We must determine whether compelling its production was precluded by some privilege available to the defense in the circumstances of this case.
[233]*233III
A
The Court of Appeals concluded that the Fifth Amendment renders criminal discovery “basically a one-way street.” 501 F. 2d, at 154. Like many generalizations in constitutional law, this one is too broad. The relationship between the accused’s Fifth Amendment rights and the prosecution’s ability to discover materials at trial must be identified in a more discriminating manner.
The Fifth Amendment privilege against compulsory self-incrimination is an “intimate and personal one,” which protects “a private inner sanctum of individual feeling and thought and proscribes state intrusion to extract self-condemnation.” Couch v. United States, 409 U. S. 322, 327 (1973); see also Beilis v. United States, 417 U. S. 85, 90-91 (1974); United States v. White, 322 U. S. 694, 698 (1944). As we noted in Couch, supra, at 328, the “privilege is a personal privilege: it adheres basically to the person, not to information that may incriminate him.” 7
In this instance disclosure of the relevant portions of the defense investigator’s report would not impinge on the fundamental values protected by the Fifth Amendment. The court’s order was limited to statements [234]*234allegedly made by third parties who were available as witnesses to both the prosecution and the defense. Respondent did not prepare the report, and there is no suggestion that the portions subject to the disclosure order reflected any information that he conveyed to the investigator. The fact that these statements of third parties were elicited by a defense investigator on respondent’s behalf does not convert them into respondent’s personal communications. Requiring their production from the investigator therefore would not in any sense compel respondent to be a witness against himself or extort communications from him.
We thus conclude that the Fifth Amendment privilege against compulsory self-incrimination, being personal to the defendant, does not extend to the testimony or statements of third parties called as witnesses at trial. The Court of Appeals’ reliance on this constitutional guarantee as a bar to the disclosure here ordered was misplaced.
B
The Court of Appeals also held that Fed. Rule Crim. Proc. 16 deprived the trial court of the power to order disclosure of the relevant portions of the investigator’s report.8 Acknowledging that the Rule appears to control pretrial discovery only, the court nonetheless determined [235]*235that its reference to the Jencks Act, 18 U. S. C. § 3500, signaled an intention that Rule 16 should control trial practice as well. We do not agree.
Both the language and history of Rule 16 indicate that it addresses only pretrial discovery. Rule 16 (f) requires that a motion for discovery be filed “within 10 days after arraignment or . . . such reasonable later time as the court may permit,” and further commands that it include all relief sought by the movant. When this provision is viewed in light of the Advisory Committee’s admonition that it is designed to encourage promptness in filing and to enable the district court to avoid unnecessary delay or multiplication of motions, see Advisory Committee’s Notes on Rule 16, 18 U. S. C. App., p. 4494, the pretrial focus of the Rule becomes apparent. The Government’s right of discovery arises only after the defendant has successfully sought discovery under subsections (a) (2) or (b) and is confined to matters “which the defendant intends to produce at the trial.” Fed. Rule Crim. Proc. 16 (c). This hardly suggests any intention that the Rule would limit the court’s power to order production once trial has begun.9 Finally, the Advisory Committee’s Notes emphasize its pretrial character. Those notes repeatedly characterize the Rule as a provision governing pretrial disclosure, never once suggesting that it was intended to constrict a district court’s [236]*236control over evidentiary questions arising at trial. 18 U. S. C. App., pp. 4493-4495.
The incorporation of the Jencks Act limitation on the pretrial right of discovery provided by Rule 16 does not express a contrary intent. It only restricts the defendant’s right of pretrial discovery in a manner that reconciles that provision with the Jencks Act limitation on the trial court’s discretion over evidentiary matters. It certainly does not convert Rule 16 into a general limitation on the trial court’s broad discretion as to evidentiary questions at trial. Cf. Giles v. Maryland, 386 U. S. 66, 101 (1967) (Fortas, J., concurring in judgment).10 We conclude, therefore, that Rule 16 imposes no constraint on the District Court’s power to condition the impeachment testimony of respondent’s witness on the production of the relevant portions of his investigative report. In extending the Rule into the trial context, the Court of Appeals erred.
IV
Respondent contends further that the work-product doctrine exempts the investigator’s report from disclosure at trial. While we agree that this doctrine applies to criminal litigation as well as civil, we find its protection unavailable in this case.
The work-product doctrine, recognized by this Court in Hickman v. Taylor, 329 U. S. 495 (1947), reflects the strong “public policy underlying the orderly prosecution [237]*237and defense of legal claims.” Id., at 510; see also id., at 514U515 (Jackson, J., concurring). As the Court there observed:
“Historically, a lawyer is an officer of the court and is bound to work for the advancement of justice while faithfully protecting the rightful interests of his clients. In performing his various duties, however, it is essential that a lawyer work with a certain degree of privacy, free from unnecessary intrusion by opposing parties and their counsel. Proper preparation of a client’s case demands that he assemble information, sift what he considers to be the relevant from the irrelevant facts, prepare his legal theories and plan his strategy without undue and needless interference. That is the historical and the necessary way in which lawyers act within the framework of our system of jurisprudence to promote justice and to protect their clients’ interests. This work is reflected, of course, in interviews, statements, memoranda, correspondence, briefs, mental impressions, personal beliefs, and countless other tangible and intangible ways — aptly though roughly termed by the Circuit Court of Appeals in this case as the ‘work product of the lawyer.’ Were such materials open to opposing counsel on mere demand, much of what is now put down in writing would remain unwritten. An attorney’s thoughts, heretofore inviolate, would not be his own. Inefficiency, unfairness and sharp practices would inevitably develop in the giving of legal advice and in the preparation of cases for trial. The effect on the legal profession would be demoralizing. And the interests of the clients and the cause of justice would be poorly served.” Id., at 510-511.
The Court therefore recognized a qualified privilege for [238]*238certain materials prepared by an attorney “acting for his client in anticipation of litigation.” Id., at 508.11 See generally 4 J. Moore, Federal Practice ¶ 26.63 (2d ed. 1974); E. Cleary, McCormick on Evidence 204-209 (2d ed. 1972); Note, Developments in the Law — Discovery, 74 Harv. L. Rev. 940,1027-1046 (1961).
Although the work-product doctrine most frequently is asserted as a bar to discovery in civil litigation, its role in assuring the proper functioning of the criminal justice system is even more vital. The interests of society and the accused in obtaining a fair and accurate resolution of the question of guilt or innocence demand that adequate safeguards assure the thorough preparation and presentation of each side of the case.12
At its core, the work-product doctrine shelters the mental processes of the attorney, providing a privileged area within which he can analyze and prepare his client's case. But the doctrine is an intensely practical one, grounded in the realities of litigation in our adversary system. One of those realities is that attorneys often must rely on the assistance of investigators and other agents in the compilation of materials in preparation for trial. It is therefore necessary that the doctrine protect material prepared by agents for the attorney as [239]*239well as those prepared by the attorney himself.13 Moreover, the concerns reflected in the work-product doctrine do not disappear once trial has begun. Disclosure of an attorney’s efforts at trial, as surely as disclosure during pretrial discovery, could disrupt the orderly development and presentation of his case. We need not, however, undertake here to delineate the scope of the doctrine at trial, for in this instance it is clear that the defense waived such right as may have existed to invoke its protections.
The privilege derived from the work-product doctrine is not absolute. Like other qualified privileges, it may be waived. Here respondent sought to adduce the testimony of the investigator and contrast his recollection of the contested statements with that of the prosecution’s witnesses. Respondent, by electing to present the investigator as a witness, waived the privilege with respect to matters covered in his testimony.14 Respond[240]*240ent can no more advance the work-product doctrine to sustain a unilateral testimonial use of work-product materials than he could elect to testify in his own behalf and thereafter assert his Fifth Amendment privilege to resist cross-examination on matters reasonably related to those brought out in direct examination. See, e. g., McGautha v. California, 402 U. S. 183, 215 (1971).15
V
Finally, our examination of the record persuades us that the District Court properly exercised its discretion in this instance. The court authorized no general “fishing expedition” into the defense files or indeed even into the defense investigator’s report. Cf. United States v. Wright, 160 U. S. App. D. C. 57, 489 F. 2d 1181 (1973). Rather, its considered ruling was quite limited in scope, opening to prosecution scrutiny only the portion of the report that related to the testimony the investigator would offer to discredit the witnesses’ identification testimony. The court further afforded respondent the maxi[241]*241mum opportunity to assist in avoiding unwarranted disclosure or to exercise an informed choice to call for the investigator’s testimony and thereby open his report to examination.
The court’s preclusion sanction was an entirely proper method of assuring compliance with its order. Respondent’s argument that this ruling deprived him of the Sixth Amendment rights to compulsory process and cross-examination misconceives the issue. The District Court did not bar the investigator’s testimony. Cf. Washington v. Texas, 388 U. S. 14, 19 (1967). It merely prevented respondent from presenting to the jury a partial view of the credibility issue by adducing the investigator’s testimony and thereafter refusing to disclose the contemporaneous report that might offer further critical insights. The Sixth Amendment does not confer the right to present testimony free from the legitimate demands of the adversarial system; one cannot invoke the Sixth Amendment as a justification for presenting what might have been a half-truth. Deciding, as we do, that it was within the court’s discretion to assure that the jury would hear the full testimony of the investigator rather than a truncated portion favorable to respondent, we think it would be artificial indeed to deprive the court of the power to effectuate that judgment. Nor do we find constitutional significance in the fact that the court in this instance was able to exclude the testimony in advance rather than receive it in evidence and thereafter charge the jury to disregard it when respondent’s counsel refused, as he said he would, to produce the report.16
[242]*242The judgment of the Court of Appeals for the Ninth Circuit is therefore
Reversed.
Mr. Justice Douglas took no part in the consideration or decision of this case.