LASKER, District Judge:
John Musacchia and Joseph Gambino appeal their convictions on one count of conspiracy to defraud the United States by willfully failing to pay gasoline excise taxes in violation of 18 U.S.C. § 371 (1988) and 26 U.S.C. §§ 7201, 7202 and 7206(2) (1982). Musacchia appeals his conviction on six additional counts of aiding and abetting evasion of such taxes.
Appellants contend that it was reversible error for the prosecution to bolster the testimony of three witnesses by eliciting testimony on direct examination that their cooperation agreements with the government required them to tell the truth. Mu-sacchia also asserts that the statute of limitations bars his prosecution on the six counts charging aiding and abetting of substantive tax evasion offenses under §§ 7201 and 7202. In supplemental briefing following the Supreme Court’s holding in Gomez v. United States, — U.S. -, 109 S.Ct. 2237, 104 L.Ed.2d 923 (1989) (holding jury selection by magistrates not authorized under the Federal Magistrates Act), appellants urge reversal because they did not consent to jury selection by a magistrate. For the reasons discussed below, we conclude that the appeals are without merit and affirm.
BACKGROUND
Musacchia owned and operated O.K. Petroleum (“O.K.”), a corporation that sold gasoline and heating oil through retail and wholesale outlets in New York State. During the period at issue federal law imposed an excise tax of nine cents on gasoline sold by producers and certain wholesale distributors. In December 1982, O.K. applied for a Registration for Tax-Free Transactions (“Form 637”) from the Internal Revenue Service (“IRS”), which would exempt the company from the excise tax. O.K.’s application was never approved. Thereafter O.K. made large purchases of gasoline from two distributors but refused to pay the distributors the money due for federal excise taxes, representing first that the purchases were tax-exempt because O.K. was about to receive, and then that it had received, a Form 637. O.K. also purchased gasoline from General Oil Distributors, Inc. (“General Oil”) in 1983 and failed to pay $270,000 in excise taxes by representing that it held a valid Form 637. When General Oil discovered that O.K. lacked a Form 637 it barred all tax-exempt sales to O.K.
Musacchia subsequently devised a “daisy chain scheme” to purchase untaxed gasoline. Under this scheme Rappaport Fuel Company (“Rappaport”), which held a valid Form 637, would purchase tax-exempt gasoline from various suppliers and then create fictitious invoices for sales to transient front companies that were not controlled by appellants, but which they formed for [496]*496the specific purpose of evading excise taxes. These companies had valid Forms 637 and operated only long enough to allow Rappaport to document the fictitious sales. Rappaport would in fact distribute the gasoline to Musacchia. Two companies that Musacchia controlled, AKA Petroleum (“AKA”) and CWM Petroleum (“CWM”) paid the distributors for the gasoline purchased by Rappaport. Through this scheme Musacchia purchased more than 8 million gallons of gasoline on which he failed to pay taxes of more than $777,000.
Gambino assisted Musacchia in forming AKA and concealing Musacchia’s involvement in the company. Gambino solicited Joseph J. Ribando, Gambino’s brother-in-law, to sign on as president of AKA and Luis Cuomo to act as Treasurer. Ribando opened a bank account and mail drop for AKA and signed checks at Gambino’s request. He had virtually no other involvement with the company. Cuomo, the treasurer, had even less involvement than Ri-bando. Both ultimately resigned. Gambi-no also helped Musacchia to operate the front companies and to persuade Herman DeJonge, the owner of Rappaport, to make untaxed sales to Musacchia.
I. BOLSTERING
During direct examination of Arthur Williams (a principal in CWM), Cuomo, Ri-bando and DeJonge, the government elicited testimony that cooperation agreements between the witnesses and the government required the witnesses to tell the truth and provided that if they lied on the witness stand they would be subject to prosecution for perjury. Appellants first objected, without stating grounds, to the prosecutor’s questions to Ribando and Williams about these “truth-telling” provisions but these objections were overruled by the judge. After the judge overruled Musacc-hia’s objection to the prosecutor’s question to DeJonge about the requirement in his agreement that he testify truthfully, defense counsel moved for a mistrial on the ground that the government had improperly bolstered the testimony of Williams, Cuomo and Siegal prior to any defense attack on their credibility.1 The judge denied the motion but gave the following curative instruction to the jury:
The government has brought out testimony from several witnesses that I’ve decided should not have been brought out concerning the possibility of being prosecuted for testifying falsely. So the testimony concerning testifying falsely, I am instructing you to disregard those statements.
Appellants now claim that, despite this curative instruction, the government’s deliberate and improper questioning of Williams, Cuomo and Ribando about the truth-telling provisions of their agreements and the court’s failure to sustain appellants’ timely objections constitute reversible error.2 The government concedes that the defense did not attack the credibility of Ribando, Cuomo and Williams before they testified but argues that even if subject to review, the error alleged by appellants was harmless because: 1) the judge gave a curative jury instruction; 2) defense counsel conceded during their argument for a mistrial that the entire testimony of Ribando and Williams was truthful, and therefore any bolstering was not prejudicial; and 3) Williams’ statement was rendered harmless by a subsequent attack on his credibility by Musacchia’s counsel and by the peripheral nature of his testimony.
The government argues at the outset that appellants’ claim of error resulting from the admission of the cooperation agreement testimony is reversible only if it [497]*497was plain error, because appellants raised only general objections to the testimony at trial. Appellants reply that their objections were “apparent from the context” under Fed.R.Evid. 103(a)(1), which states that a specific ground for objection need be raised only “if the specific ground was not apparent from the context.” Based on a review of the trial transcript, it is clear that appellants’ objections were apparent from the context. Defense counsel specifically objected to questions about the truth-telling provisions of the agreements and not to the testimony that the cooperation agreements were entered into by the witnesses.3 Accordingly, the objections were preserved for review.
This court has consistently held that:
Because of the bolstering potential of cooperation agreements ... we have permitted such agreements to be admitted in their entirety only after the credibility of the witness has been attacked_ [Bolstering aspects [of cooperation agreements] such as promises to testify truthfully or penalties for failure to do so may only be developed to rehabilitate the witness after a defense attack on credibility.
United States v. Cosentino, 844 F.2d 30, 33 (2d Cir.), cert. denied, — U.S. -, 109 S.Ct. 303, 102 L.Ed.2d 322 (1988) (footnote and citations omitted); see United States v. Jones, 763 F.2d 518, 522 (2d Cir.), cert. denied, 474 U.S. 981, 106 S.Ct. 386, 88 L.Ed.2d 339 (1985). However, in United States v. Arroyo-Angulo, 580 F.2d 1137, 1146-47 (2d Cir.), cert. denied, 439 U.S. 913, 99 S.Ct. 285, 58 L.Ed.2d 260 (1978), we held that because defense counsel challenged the credibility of a government witness in the opening statement and later in cross-examination and during summation, such challenge was inevitable, and rendered harmless the error in admitting the witness’s cooperation agreement into evidence during direct examination.
The government concedes that it was error to question the witnesses about the truth-telling provisions prior to defense challenges to credibility but contends that such error was harmless. Appellants argue that because the prosecutor intentionally bolstered the testimony of its witnesses the error cannot be deemed harmless under United States v. Borello, 766 F.2d 46, 56 (2d Cir.1985), in which the court held that the admission of and reading from the truth-telling portions of a cooperation agreement on direct examination were not harmless error even though the defense subsequently challenged part of Borello’s testimony. The Borello court did not find it necessary to engage in harmless error analysis, id. at 58, stating:
[W]e have previously suggested that an Arroyo-Angulo error is harmless if the defendant subsequently attacks the witness’s credibility. [United States v. Barnes, 604 F.2d 121, 151 (2d Cir.1979).] The error, however, cannot always be harmless.... [W]here we have spelled out in a series of cases the procedure for introducing cooperation agreements ... [f]or us to disapprove of the ... bolstering of the witness’s testimony and then to declare it harmless error would make our remarks in the previous cases purely “ceremonial.” The error cannot be deemed harmless.
Id. at 57-58. Appellants argue that because the prosecutor in this case deliberately questioned the witnesses regarding the truth-telling provisions of the agreements knowing such questioning was improper under the case law of this Circuit, the error in this case cannot be harmless and no harmless error analysis is required under Borello. As evidence of the intentional nature of the error appellants note that, during argument in the robing room on Musacchia’s motion for a mistrial, a member of the prosecution team offered to withdraw the questions about the truth-telling provisions of DeJonge’s agreement.
We disagree with appellants’ assertion that the prosecutor intentionally violated the rule against questioning the witnesses about truth-telling provisions of their [498]*498agreements on direct examination prior to any defense attack on credibility. Indeed, the government contended during the argument on Musacchia’s motion for a mistrial, that it construed Musacchia’s counsel’s opening statement challenge to DeJonge’s credibility as an attack on the credibility of all witnesses, permitting the challenged questions. By contrast, in Borello, defense counsel did not attack the credibility of the cooperating prosecution witness during the opening statement, leading the court to conclude that the prosecution had intentionally violated the law. Moreover, Borello did not establish a per se rule that such errors can never be deemed harmless but rather that they cannot always be harmless. We conclude that the government had a good faith basis for asking the challenged questions. Accordingly, Borel-lo does not bar an examination of the government’s claims that the error was harmless.
The government contends that, because defense counsel argued during the trial that Ribando and Cuomo were telling the truth, any bolstering of their testimony was irrelevant to the outcome of the trial. During argument on the mistrial motion, Musacchia’s counsel stated:
In fact the defense has been that Williams, Cuomo and Ribando are all telling the truth but that we have an explanation for why they were used in this fashion. Their credibility was not attacked, and at least two of them I didn’t ask questions of.... They weren’t attacked or questioned in any fashion, and as a matter of fact as I’ve stated we adopt their testimony.
Based on this statement the government asserts that the defense conceded the truthfulness of Cuomo’s and Ribando’s testimony and, accordingly, there was no. significant chance that the outcome of the trial was affected by the error. Moreover, according to the government, counsel for Musacchia subsequently attacked Williams’ credibility by arguing in summation that Williams had “lied,” thereby rendering his earlier testimony about the truth-telling portions of the agreement admissible under Arroyo-Angulo.
Appellants assert that accepting the government’s argument — that the error is harmless because Williams’ credibility was challenged and Ribando and Cuomo’s testimony was not challenged — is tantamount to holding that such an error can never be harmless, contrary to the holding in Borel-lo.
However, appellants have not specified how they were prejudiced by the error. Appellants do not dispute that Williams’ testimony was peripheral.4 Their admission during trial that their strategy involved characterizing the testimony of Cuo-mo and Ribando as truthful lessens the effect of the error with respect to those witnesses. Most importantly, Judge Wex-ler gave a clear curative instruction to the jury not to consider the challenged testimony regarding the truth-telling portions of the cooperation agreements. Given the good faith belief by the prosecutor that the credibility of all the witnesses had been put into question by Musacchia’s opening statement and for the reasons discussed above, we conclude that the admission of testimony regarding the truth-telling requirements of the cooperation agreements on direct examination was harmless error.
II. APPLICABLE STATUTES OF LIMITATION
Musacchia contends that the applicable statutes of limitation bar his prosecution and subsequent conviction for the substantive crimes charged in counts 2 through 7 of the indictment. The indictment in this case was filed nearly four years after the date of the last act relating to counts 2 through 7. Musacchia asserts that the applicable statute of limitations for counts 2 through 7 is three years; the [499]*499district court held that the applicable limitations period was six years. 696 F.Supp. 1548, 1550 (E.D.N.Y.1988).
The statute of limitations for criminal prosecutions arising under the internal revenue laws is found in 26 U.S.C. § 6531 (1982), which states in relevant part:
No person shall be prosecuted, tried, or punished for any of the various offenses arising under the internal revenue laws unless the indictment is found or the information instituted within 3 years next after the commission of the offense, except that a period of limitation shall be 6 years—
(1) for offenses involving the defrauding or attempting to defraud the United States or any agency thereof, whether by conspiracy or not, and in any manner;
(2) for the offense of willfully attempting in any manner to evade or defeat any tax or the payment thereof;
(3) for the offense of willfully aiding or assisting in, or procuring, counseling, or advising, the preparation or presentation under, or in connection with any matter arising under, the internal revenue laws, of a false or fraudulent return, affidavit, claim, or document (whether or not such falsity or fraud is with the knowledge or consent of the person authorized or required to present such return, affidavit, claim, or document).
The numbered sections above describe offenses carrying a special six-year limitations period rather than the general three-year statute of limitations for internal revenue offenses. Musacchia claims that because § 6531(3) is the only internal revenue offense carrying a six-year statute of limitations which uses the term “aiding, or assisting,” the aiding and abetting of all other substantive internal revenue offenses must carry the general three-year statute of limitation. Accordingly, he argues, counts 2, 4 and 5 of the indictment, under which he was convicted of aiding and abetting violations of 26 U.S.C. §§ 7201 and 7202, must be dismissed as untimely.
In support of this argument, Musacchia notes that other specifically enumerated exceptions to the general three-year statute of limitation explicitly refer to specific offenses under the code by section number. For example, 26 U.S.C. § 6531(7) provides that one of the exceptions is “for offenses described in section 7214(a),” which relates to intimidation of officers and employees of the United States. Musacchia asserts that if Congress had intended, as the government argues, to include a particular substantive offense (in this case § 7202 or § 7201) among those covered by § 6531(3) it could have done so by reference to that offense; because it did not do so with respect to the offense at issue the six-year statute of limitations applies only to the offense of aiding and abetting the filing of a false return and not to aiding and abetting of the offenses defined in 26 U.S.C. §§ 7201 and 7202 (counts 2, 4 and 5).
In United States v. Campbell, 426 F.2d 547, 553 (2d Cir.1970), this court held that the applicable statute of limitations for the offense of aiding and abetting under 18 U.S.C. § 2 is the statute for the substantive offense charged. The court observed:
18 U.S.C. § 2 does not define a crime; rather it makes punishable as a principal one who aids or abets the commission of a substantive crime.... Clearly one can violate [26 U.S.C.] § 7214(a) as an aider and abettor, and the offense, not the persons involved, determines the applicability of the six-year period of limitation.
Id. Musacchia fails to address Campbell but its analysis controls in this case. Accordingly, the statute of limitations for the substantive counts charged in the indictment apply in this case. Counts 2, 4, and 6 charge aiding and abetting violations under 26 U.S.C. § 7201, which carries a six-year limitations period as explicitly provided in 26 U.S.C. § 6531(2). It follows that the statute of limitations does not bar prosecution of these counts.
Counts 3, 5, and 7 charge aiding and abetting under 26 U.S.C. § 7202 — willful failure to account for and pay over gasoline excise taxes. Musacchia argues for the first time on appeal that § 7202 carries a three-year rather than a six-year statute of limitations. Section 6531(4) mandates a six-year statute of limitations “for the of[500]*500fense of willfully failing to pay any tax.” 5 In United States v. Porth, 426 F.2d 519, 521-22 (10th Cir.), cert. denied, 400 U.S. 824, 91 S.Ct. 47, 27 L.Ed.2d 53 (1970), the court held, without analysis, that § 7202 falls within the six-year statute of limitations exception of § 6531(4). Musacchia relies on a more recent district court decision which held to the contrary, United States v. Block, 497 F.Supp. 629 (N.D.Ga.), aff'd, 660 F.2d 1086 (5th Cir.1980). Block held that the language of § 6531(4) does not track the language of § 7202:
It seems unlikely to the Court that Congress would have used the language of so many of the § 7201 et seq. code sections when drafting the subsections of § 6531 but omit use of the key words of § 7202 if it had intended to make failure to “pay over” third party taxes subject to the six-year statute of limitations.
497 F.Supp. at 632. A second factor in the Block court's determination was that
[Section] 6531(4) is directed at “the offense of willfully failing to pay any tax....” (emphasis added), not a class of offenses. It is quite clear that failure to “pay over” third party taxes [under § 7202] is substantively different from failure to pay taxes. See Slodov v. United States, 436 U.S. 238, 248-50, 98 S.Ct. 1778, 1785-1787, 56 L.Ed.2d 251 (1978).
Id. (footnote omitted).
The Block court’s analysis is not convincing. Although § 6531(4) does not track the language of § 7202 precisely, in the Supreme Court’s decision in Slodov v. United States, 436 U.S. 238, 249, 98 S.Ct. 1778, 1786, 56 L.Ed.2d 251 (1978), the terms “pay” and “pay over” were used interchangeably. In Slodov, the Court interpreted 26 U.S.C. § 6672, which applies to “[a]ny person required to collect, truthfully account for, and pay over any tax,” as applying “only to failure to pay taxes.... ” 436 U.S. at 249, 98 S.Ct. at 1786. Although the Court was analyzing a different provision of the code — the significance of the word “any” modifying the word “person” under § 6672 — and did not focus on the distinction argued by appellants in this case, it is still significant that the Court used the terms “pay over” and “pay” synonymously.
The government persuasively argues that it would be inconsistent for Congress to have prescribed a six-year limitation period for the misdemeanor offense defined in 26 U.S.C. § 7203 (failure to file a return or pay a tax)6 while providing only a three-year limitation period for the felony offense defined in § 7202. Moreover, the language of § 6531(4) — applying the six-year statute of limitations to “the offense of willfully failing to pay any tax, or make any return ... at the time or times required by law or regulations” — suggests that it applies to any of several sections of the Code that define such an offense. For these reasons we find the reasoning of Block unpersuasive and conclude that a six-year statute of limitations applies to the offense defined by 26 U.S.C. § 7202 and thus to counts 3, 5 and 7 in the indictment. Accordingly, Musacchia’s prosecution and conviction were not barred by the applicable statutes of limitation.
CARDAMONE, Circuit Judge:
We concur in our colleague Judge Lasker’s thorough discussion of Part I (Bolstering) and Part II (Statute of Limitations), which concludes that nothing occurred during the trial which would warrant reversal [501]*501of Musacchia’s and Gambino’s convictions on the merits.
III. JURY SELECTION BY A MAGISTRATE
Following oral argument of this appeal on March 6, 1989, we granted a motion on August 80,1989 to withhold decision on the appeal until supplemental briefs could be submitted on the issue of whether the magistrate conducting voir dire of the jury warrants reversal in light of Gomez v. United States, — U.S. -, 109 S.Ct. 2237, 104 L.Ed.2d 923 (1989). Having now received and considered the supplemental briefs filed by appellants and the government, we turn to this issue. Appellants argue that their convictions must be reversed. We disagree and vote to affirm.
The Supreme Court in Gomez addressed the question of “whether presiding at the selection of a jury in a felony trial without the defendant’s consent is among those ‘additional duties’ ” permitted a magistrate under 28 U.S.C.A. § 636(b)(3) (West Supp. 1989). Gomez, 109 S.Ct. at 2239. Section 636(b)(3), part of the Federal Magistrates Act, limits the duties that may be assigned a magistrate to those which the magistrate could execute without being “inconsistent with the Constitution and laws of the United States.” Gomez concluded that § 636(b)(3) did not grant magistrates authority to preside over voir dire in a criminal trial. Because “[ajmong those basic fair trial rights that ‘ “can never be treated as harmless” ’ is a defendant’s ‘right to an impartial adjudicator, be it judge or jury,’ ” the Court concluded that “harmless-error analysis does not apply in a felony case in which, despite the defendant's objection and without any meaningful review by a district judge, an officer exceeds his jurisdiction by selecting a jury.” 109 S.Ct. at 2248.
Since the Supreme Court’s holding there have been a number of circuit court opinions addressing the issues of (1) whether Gomez established a jurisdictional bar to magistrates presiding over voir dire, and (2) whether reversal is mandated where a defendant prior to Gomez either consented or failed to object to empanelment before a magistrate. In two cases handed down subsequent to Gomez, we held that Gomez did not create a jurisdictional bar to a magistrate conducting voir dire, and that reversal is not mandated when a defendant, prior to that decision, consented or failed to object to empanelment by a magistrate. See United States v. Vanwort, 887 F.2d 375, 382-83 (2d Cir.) (failure to object), petition for cert. filed (Dec. 21, 1989); United States v. Mang Sun Wong, 884 F.2d 1537, 1546 (2d Cir.1989) (explicit consent), cert. denied, — U.S. -, 110 S.Ct. 1140, 107 L.Ed.2d 1045 (1990).
Here appellants, who were tried before Gomez was filed, neither consented nor objected to voir dire by a magistrate. Under Vanwort, there is no question that we do not find reversal warranted in these circumstances. Appellants contend — and the dissenting opinion concludes — that we may distinguish the instant case from Van-wort because in this case the jury was selected after our holding in United States v. Garcia, 848 F.2d 1324, 1332 (2d Cir.1988), rev’d sub nom. Gomez v. United States, — U.S. -, 109 S.Ct. 2237, 104 L.Ed.2d 923 (1989), which stated that “even absent a defendant’s consent [and where a defendant explicitly objects] the Federal Magistrates Act permits district courts to delegate the task of jury selection in felony cases to a magistrate.” We think the distinction irrelevant.
In making this argument, appellants rely upon United States v. France, 886 F.2d 223 (9th Cir.1989). There, faced with a factual situation identical to that now before us, the court held that failure to object would not amount to a waiver because two earlier circuit cases “presented [the defendant] with a ‘solid wall of circuit authority’ ... [that] had already decided, erroneously, that magistrates could conduct voir dire in felony trials. Any objection to the magistrate performing voir dire ... would, therefore, clearly have been futile.” Id. at 228. France was predicated on two Ninth Circuit en banc opinions establishing that a defendant was excused from making a contemporaneous objection when there was a [502]*502“solid wall of authority” that would have' prevented a district court from upholding the defendant’s objection. Id. at 227-28.
Significantly, we have not established an exception to the contemporaneous objection requirement in areas where there is a “solid wall of authority” running contrary to the defendant’s objection. The only authority even suggesting an analogous principle in this Circuit is a footnote, cited in the dissenting opinion, in United States v. Indiviglio, 352 F.2d 276 (2d Cir.1965) (en banc), cert. denied, 383 U.S. 907, 86 S.Ct. 887, 15 L.Ed.2d 663 (1966). The footnote acknowledges that under plain-error analysis “[ajppellate courts often notice error not objected to below when, under the law existing at the time of the trial, objection would have been futile and when error was asserted on review on the basis of a subsequent appellate decision.” Id. at 280 n. 7. This single line cannot be said to establish a circuit wall-of-authority exception similar to that relied upon by the Ninth Circuit.
Nor did Garcia itself create authority sufficient to cause defense counsel to believe any objection to jury empanelment before a magistrate would be futile. The decision in Garcia was promptly appealed to the Supreme Court and reversed a year later. In contrast, the Ninth Circuit already had ruled in two cases decided four years prior to Gomez — certiorari had been denied in both — that magistrates were empowered to conduct voir dire under the Federal Magistrates Act. See United States v. Peacock, 761 F.2d 1313 (9th Cir.), cert. denied, 474 U.S. 847, 106 S.Ct. 139, 88 L.Ed.2d 114 (1985); United States v. Bezold, 760 F.2d 999 (9th Cir.1985), cert. denied, 474 U.S. 1063, 106 S.Ct. 811, 88 L.Ed.2d 786 (1986). Thus, the posture of the issue in our Circuit is more akin to that existing in the First Circuit where “[tjhere was no binding rule ... such as necessarily foredoomed an objection to magistrates’ empaneling.” United States v. Lopez-Pena, Nos. 87-2003 through 87-2008, slip op. at 15-16 (1st Cir. Nov. 22, 1989) (rehearing en banc filed Dec. 20, 1989).
Appellants additionally claim that Gomez states that a magistrate is without jurisdiction under the Federal Magistrates Act to conduct voir dire. We disagree. Since Gomez was decided we and other circuits have focused on the “without defendant’s consent” language and generally ruled that where there is either consent or a failure to object a magistrate may conduct the jury voir dire in a felony case. See Vanwort, 887 F.2d at 382-83; Wong, 884 F.2d at 1544; Lopez-Pena, supra, slip op. at 17-18 (not plain error to permit magistrate to preside since objection to magistrate must be raised or it is waived); Government of the Virgin Islands v. Williams, 892 F.2d 305, 310 (3d Cir.1989) (absent demand no constitutional difficulty under § 636(b)(3) with delegating jury selection to magistrate); United States v. Ford, 824 F.2d 1430, 1438-39 (5th Cir.1987) (en banc) (harmless error for magistrate to conduct voir dire where defendant failed to object), cert. denied, 484 U.S. 1034, 108 S.Ct. 741, 98 L.Ed.2d 776 (1988); United States v. Wey, 895 F.2d 429 (7th Cir.1990) (jury selection by magistrate is not plain error where no prejudice is shown). Con-cededly, France concluded otherwise. The court there ruled that defendant’s failure to contemporaneously object to the magistrate conducting jury selection did not waive her right to appellate review. 886 F.2d at 226. But that holding may be explained, as noted earlier, by what the court perceived as the futility of defendant raising an objection below.
We think that the magistrate had subject matter jurisdiction to conduct the voir dire in this case. Federal courts are courts of limited jurisdiction empowered to hear only those cases within the judicial power of the United States, as set forth in Article III of the Constitution, and those over which Congress has conferred to them a jurisdictional grant. See, e.g., Marbury v. Madison, 5 U.S. (1 Cranch) 137, 173-80, 2 L.Ed. 60 (1803). From this principle, it has been a commandment etched into the edifice of federal jurisprudence for over 150 years that parties cannot confer subject matter jurisdiction on a federal court, not granted it by the Constitution and Congress, although they may be willing and even anxious for the court to hear and determine the case. See Jackson v. Ashton, 33 U.S. [503]*503(8 Pet.) 148, 149, 8 L.Ed. 898 (1834); cf. American Fire & Casualty Co. v. Finn, 341 U.S. 6, 17-18 & n. 17, 71 S.Ct. 534, 542 & n. 17, 95 L.Ed. 702 (1951). Thus, when the Supreme Court stated that “[a] critical limitation on [the magistrate’s] jurisdiction is consent,” it plainly was not referring to the subject matter jurisdiction of the district court over a felony criminal trial. Gomez, 109 S.Ct. at 2244.
Instead, we think the “consent” language has reference to waivable matters under the Federal Rules of Criminal Procedure. Under Fed.R.Crim.P. 12 certain kinds of motions in a criminal prosecution must be raised before trial or they are waived. There are five numbered subdivisions of Rule 12(b) listing such defenses, objections and requests. Lack of subject matter jurisdiction, is not included among these waivable objections, and may be raised at any time. Fed.R.Crim.P. 12(b)(2). Subdivision (1) of Rule 12(b) provides for an objection based on defects in the institution of the prosecution. It is in this category of objectionable matters that the improper selection of the jury by a magistrate falls. It is a “fair trial” right to have an Article III judge conduct voir dire of the jury, see Gomez, 109 S.Ct. at 2248, and for the district court to direct the magistrate to perform it is a defect in the institution of the prosecution.
Unable to square the Supreme Court’s use of the word “jurisdiction” with traditional notions of subject matter jurisdiction, see Gomez, 109 S.Ct. at 2244-45 (magistrate’s present expanded criminal trial jurisdiction depends on consent), we believe that what Gomez intended was that — absent Congress’ grant of authority in the magistrate to perform jury selection in a felony case — the improper reference to a magistrate is a waivable defect that must be raised within the time permitted by Fed. R.Crim.P. 12(c) or it is waived under Rule 12(b). Thus, a magistrate’s lack of jurisdiction to act absent consent is analogous to a district court’s lack of jurisdiction over the person, which is also a defense that is waived unless promptly asserted. See United States v. Grote, 632 F.2d 387, 388-89 (5th Cir.1980) (failure to object to personal jurisdiction of trial court because of faulty arrest warrant waived objection); 1 Wright, Federal Practice and Procedure: Criminal 2d § 193 (1982) (collecting cases). We conclude that the defendant’s failure to make a contemporaneous objection to the delegation of jury selection to a magistrate thereby waives the objection. Like our sister circuits, we do not find empanelment before a magistrate reversible on appeal as “plain error.” See Fed.R.Crim.P. 52(b).
In any event, we are constrained by our panel holdings in Vanwort and Wong to rule that appellants, not having raised objection to the magistrate’s selection of the jury, waived their right to reversal on appeal. Hence, the judgments of conviction must be affirmed.
Judgments affirmed.