OPINION OF THE COURT
Appellant Oscar Clemons raises several issues relating to his conviction on drug-related charges. Only two points, however, merit in-depth treatment. First, Clemons contends the government violated his fifth and sixth amendment rights when the prosecutor used peremptory challenges to strike the only two blacks on the jury panel.
See Batson v. Kentucky,
For reasons that follow, we will affirm the judgment of the district court,
I. FACTS AND PROCEEDINGS BELOW
Clemons was charged in a nine-count indictment, tried by a jury, and subsequently convicted of: (1) conspiring to possess and distribute cocaine, percodan, preludin, heroin, and dilaudid, 21 U.S.C. § 846 (Count I); (2) possessing with the intent to distribute heroin and cocaine, id. § 841(a)(1) (Counts IV-VII); and (3) knowingly, intentionally and unlawfully intimidating and threatening another person to withhold testimony from an official proceeding, 18 U.S.C. § 1512(a)(1), (2)(A) (Count VIII). The district court sentenced him on July 16, 1985, to concurrent ten-year prison terms, followed by twenty years of special parole. 2 On March 23, 1987, the court denied Clemons’ requests for judgment of acquittal and for a new trial.
For purposes of this appeal, we need only examine facts relating to his pretrial voir dire challenge and his involvement with a co-conspirator and immunized witness, Gregory Dennis.
A. Jury Selection
Immediately following voir dire, Clemons, who is black, made a timely objection to the government’s use of peremptory challenges to exclude the only two black members of the jury panel. Although the Supreme Court had not yet decided
Batson,
Clemons noted its pendency and the possibility that the Court would reconsider the holding of
Swain v. Alabama,
The court denied Clemons’ request for a hearing, but nevertheless directed the prosecutor to state on the record his reasons for striking the only two blacks from the panel. The prosecutor explained:
My notes indicate that I struck every single person who was nonmarried and young. And both of those people are single, and, of course, not married, and young.
App. at 168.
Eight panel members — numbers 77, 103, 95, 59, 107, 82, 84, and 172 — were single. See App. at 18 (jury sheet), 20-63 (jury qualification sheets). Of this group, five— numbers 77, 103, 95, 59, and 107 — were considered “young,” based on the prosecutor’s criterion that anyone under age thirty-five is young. The government used peremptory challenges to strike four of the five “young single” individuals, two of whom were black. The fifth individual, a thirty-four-year-old management-level employee was not challenged, but was ultimately struck by Clemons.
Of the remaining single panel members, two — ages fifty and sixty-three, were both selected, and the third, age fifty-eight, was struck by Clemons. Finally, the government used its remaining challenges to strike three married individuals, one of whom was a news reporter vaguely familiar with the case.
B. Witness Intimidation
At trial, the government presented sufficient evidence that between March, 1981 and August, 1983, Clemons conspired with Ralph Dickinson, Scott Cornish, Donald Bishop, Gregory Dennis, Billy Lee, and others to distribute narcotics in the Union-town/Brownsville section of Pennsylvania. Cornish, Dennis, Bishop, and two others— all prior felons — testified against Clemons pursuant to a grant of immunity. Our focus is the involvement of Dennis.
Gregory Dennis, who lived in Detroit in 1980-82, testified that his brother, Bishop, introduced him to Clemons. In early 1983, Clemons asked Dennis and Bishop to accompany him to Detroit to obtain heroin from two suppliers Dennis had met during his stay there. According to Dennis, he and Clemons eventually made five or six other trips to Detroit, and on one trip, Clemons showed Dennis the motel where he stayed when he made trips to Detroit with other co-conspirators.
Clemons’ § 1512 conviction stems from the following events. On April 27, 1984, the government granted Dennis immunity from prosecution in return for his testimony before the grand jury and in subsequent trials. Dennis testified that on June 9, 1984 — after his April grand jury appearance — Clemons approached him in front of his mother’s house, where he resided. Clemons said he knew Dennis was scheduled to be a state witness against him and that “his boys wanted to come and do something to [Dennis]_” App. at 397. Dennis said he interpreted the remark to mean that Clemons’ boys intended to either “beat me up or hurt me real bad....” App. at 398. In addition, Dennis testified that Clemons also told him that another potential prosecution witness had already reconsidered and refused to testify as promised. Dennis informed the Pennsylvania State Police of the conversation, and said he feared for his life. App. at 398-99, 400.
Clemons again visited the Dennis home on June 25, 1984, asking to speak to Dennis. Dennis remained in the basement, refusing to meet with Clemons, who nonetheless spoke with Dennis’s mother Versie. Clemons told Versie Dennis and her companion David Ervin that Dennis probably didn’t want to see him because Dennis’s *745 name was on appellant’s arrest papers. He then questioned why Dennis would have testified against him, suggested that some people might want to do something to Dennis, and said that he didn’t want to get the people from Detroit “riled up.” See App. at 359, 370-71. Versie Dennis testified that Clemons said he “wouldn’t do nothing to [her son], but maybe somebody else would.” App. at 357. After Clemons left, Versie Dennis asked Gregory Dennis to leave home because she feared that her other children might be injured. App. at 359. After Versie Dennis testified before a federal grand jury, Clemons returned to her home, but she refused to speak with him. App. at 360. On cross-examination, however, Versie Dennis said Clemons never threatened her and that she feared for her family’s safety because she had had other unpleasant experiences with the “drug world.” App. at 365-67.
II. UNCONSTITUTIONAL USE OF PEREMPTORY CHALLENGES
Until the Supreme Court’s decision in
Batson,
In
Batson,
the Court held that use of peremptory challenges to strike blacks from a jury panel may raise an inference of discrimination requiring the prosecutor to come forward with a racially neutral explanation for his action.
Batson,
Once a defendant establishes a prima facie case, the prosecutor must then give a neutral, nonpretextual explanation for challenging members of that racial group.
Id.
(citing
McCray,
*746 Although the district court, “out of an abundance of caution,” App. at 168, instructed the prosecutor to justify his reasons, the court never determined whether Clemons satisfied the threshold requirement of a prima facie case of discrimination. As we shall demonstrate, see infra, this omission does not require remand.
On appeal, the government urges us to adopt a per se rule that no prima facie case of purposeful discrimination exists unless a certain number or percentage of the challenged jurors are black. Specifically, the government contends that Clemons could not have established a prima facie case because although two blacks were struck, no discriminatory inference arises when they were the only blacks on the panel, and most likely would have been struck in any event. We reject such a rule as contrary to the letter and spirit of Batson.
In
Batson,
the prosecutor used peremptory challenges to strike all four blacks on the panel, thereby permitting an all-white jury to judge a black defendant.
Batson,
Accordingly, we find that establishing some magic number or percentage to trigger a
Batson
inquiry would short-circuit the fact-specific determination expressly reserved for trial judges.
“Batson
does not require that the government adhere to a specific mathematical formula in the exercise of its peremptory challenges.”
United States v. Montgomery,
The government relies primarily on
Commonwealth v. Robinson,
At least one court of appeals seems to have fashioned a per se rule establishing a prima facie case whenever all members of defendant’s race are struck without cause.
*747
In
United States v. Chalan,
The Ninth Circuit, in dicta, appears to advocate a contrary rule. In
United States v. Vaccaro,
Other
post-Batson
decisions have eschewed a bright-line rule. In
Montgomery,
Striking a single black juror could constitute a prima facie case even when blacks ultimately sit on the panel and even when valid reasons exist for striking other blacks.
See United States v. Gordon,
In view of the various jury selection practices and the unique racial makeup of each judicial district, we are unwilling to
*748
depart from Batson’s reliance on the trial judge’s expertise in assessing a prima facie case. Although it may be easier to establish a prima facie case when all blacks are excluded from a jury, or when one or two blacks are excluded from a panel in a district with a relatively low black population, we cannot say the conclusion is automatic. Indeed,
Batson
presented a case in which all blacks were excluded,
see
When assessing the existence of a prima facie case, trial judges should examine all relevant factors, such as: how many members of the “cognizable racial group” (in this case, blacks) are in the panel; the nature of the crime; and the race of the defendant and the victim.
See generally United States v. Allen,
In sum, we reject the government’s position that there could be no prima facie case of discrimination under Batson because only two blacks were struck; 6 rather such a finding would clearly have been permissible here.
For purposes of this appeal we assume that Clemons could satisfy the Bat-son standard for establishing a prima facie case. Accordingly, we must determine whether the prosecutor articulated a racially neutral, nonpretextual reason for excluding the only two black jurors from the panel in this case.
When challenged by the court, the prosecutor explained he was striking young, single panel members. His explanation is logical in the context of a narcotics prosecution. The only young, single individual not struck was age thirty-four, at the outer edge of the prosecutor’s admittedly subjective age limit, and held a management-level position. The prosecutor’s justification was “clear and reasonably specific,” and exceeded the self-serving explanations expressly rejected by the Court in Batson. See id. at 1723-24 & n. 20 (intuition and good faith insufficient to rebut prima facie case). 7 Moreover, the Court in Batson did *749 not handcuff a prosecutor’s legitimate exercise of peremptory strikes. Although the Court condemned the practice of abusing peremptory challenges to further discriminatory ends, it reaffirmed the importance of peremptory challenges as a trial procedure, and declined an invitation to abolish the process. See id. at 1724 & n. 22.
Accordingly, the prosecutor’s explanation complied with the Batson standard, and Clemons’ Batson claim must be rejected.
III. CONSTITUTIONALITY OF 18 U.S.C. § 1512(c)
Clemons was charged with using threats and intimidation with the intent of influencing another person’s testimony and inducing that person to withhold testimony. See App. at 15 (Indictment, Count VIII); 18 U.S.C. § 1512(a)(1), (2)(A). The affirmative defense, meanwhile, permits a defendant to establish that the conduct “consisted solely of lawful conduct and” was undertaken with the sole intent “to encourage, induce, or cause the other person to testify truthfully.” See 18 U.S.C. § 1512(c) (emphasis supplied). 8
Clemons’ constitutional argument is straightforward. He contends that by requiring him to show that his conduct was lawful and carried out with an intent to encourage truthful testimony, Congress has forced him to “come forward with direct opposing evidence of ‘intent....’”
See
Brief for Appellant at 14. The government, meanwhile, contends that the statute is constitutional because § 1512(a)(1), (2)(A) requires it to establish every element of the offense. Indeed, the statute unambiguously requires the government to establish: (1) the knowing use of intimidation, physical force, or threats; and (2) the intent to influence the testimony of another person in an official proceeding or the intent to cause or induce another person to withhold testimony. Accordingly, the government argues, by permitting a defendant to establish lawfulness or good intentions, § 1512(c)’s affirmative defense provides a defendant with an opportunity “to prove additional facts, which would make otherwise illegal conduct lawful.”
See
Brief and Supplemental Appendix on Behalf of the United States at 33 (citing
United States v. Kalevas,
A. Is a Constitutional Issue Presented?
Our inquiry, of course, must proceed within the bounds of the caveat that assessing the constitutionality of an Act of Congress is our “gravest and most delicate duty.”
Blodgett v. Holden,
Similarly, we must refrain from deciding a constitutional question unless necessity
*750
obliges us to do so.
Ashwander v. TVA,
As a threshold matter, we must determine whether the affirmative defense of § 1512(c) was implicated here. If the affirmative defense was not implicated by argument or evidence at trial, or was not presented to the jury in the court’s charge, we must avoid deciding the constitutional question. This case is troublesome because although the statute requires the defendant to prove the § 1512(c) defense, Clemons did not expressly invoke the statute, or the defense it sets forth, until the charging conference. Moreover, in its jury instruction, the court attempted to avoid the burden-shifting problem by rephrasing the statutory requirements to relieve Clemons of the burden of establishing the defense. For reasons that follow, we conclude that despite the court’s attempt to modify § 1512(c), the jury could have reasonably concluded that Clemons bore the burden of proving he induced Dennis to testify truthfully.
The applicability of § 1512(c) arose when Clemons, despite doubts as to the section’s constitutionality, see Jeffries, The New Federal Witness Tampering Statute, 22 Am.Crim.L.Rev. 1, 16 (1984), requested an instruction on that provision. Clemons, however, asked the court to label § 1512(c) a “defense” and to ignore the statute by requiring the government to bear the burden of disproving the defense beyond a reasonable doubt.
Following a lengthy debate, see App. at 1767-95, the court described § 1512(c)’s “affirmative defense” as a “defense,” and declined to read the statutory language to the jury. See Supp.App. at 1794. 9 Specifically, the court instructed the jury that: (1) Clemons never has a burden to prove anything, including the affirmative defense of § 1512(c); (2) the government always maintains the burden of proving all elements of the offense; and (3) Clemons must be found not guilty “if it is proved” that his conduct was lawful and undertaken with the sole intent to cause Dennis to testify truthfully. See Supp.App. at 1786, 1788-95. 10 The critical portion of the charge was:
*751 All of those things have to be proved, each one of them, beyond a reasonable doubt by the government regardless of that matter that I have just mentioned concerning the fact that Clemons’ conduct may have been solely lawful and proper. So the government always has the burden. Mr. Clemons has no burden of proving anything of any kind. However, if it is proved that his conduct consisted solely of lawful conduct and that his sole intention was to encourage, induce or cause Greg Dennis to testify truthfully, then he would be found not guilty of that charge.
Supp.App. at 1795.
Although the court emphasized the government’s burden of proof and Clemons’ corresponding lack of burden at seventeen different points in its charge on Count Eight (§ 1512), see Supp.App. at 1786-89; 1794-95, we conclude that the court’s instruction that, “Clemons must be found not guilty if it is proved_”, was sufficient to place the burden-shifting aspect of § 1512(c) before the jury.
To be sure, we must read jury instructions in their entirety,
see Cupp v. Naughten,
The Supreme Court recently addressed a similar problem in
Francis v. Franklin,
‘[t]he acts of a person of sound mind and discretion are presumed to be the product of the person’s will, but the presumption may be rebutted and ... [a] person of sound mind and discretion is presumed to intend the natural and probable consequences of his acts but the presumption may be rebutted.’
Francis,
*752
In the course of its holding, and most important for purposes of our inquiry, the Court rejected the government’s claim that earlier portions of the charge — emphasizing the government’s burden and the defendant’s “presumed innocent” status— “explained the proper allocation of burdens with sufficient clarity.”
Id.
at 319,
The Court’s determination in Francis that the ambiguous jury instruction in that case violated due process convinces us that a comparable shortcoming in this jury charge at least presents for our review the constitutional issue of § 1512(c)’s validity. Although the court’s repeated references to Clemons’ lack of burden of proving anything in this case raises a close question, a reasonable jury could have understood the challenged portion of the charge as requiring defendant to disprove the crucial element of intent.
B. Constitutionality of § 1512(c)
Merely labelling something an affirmative defense does not mean the statute is constitutional. “[I]t must appear that the so-called defense does not in actuality negate any element of the crime.” 1 W. LaFave & A. Scott,
Substantive Criminal Law
§ 1.8, at 75 (1986);
see generally Sandstrom,
tion or excuse, but not with respect to those that “negative guilt by cancelling out the existence of some required element of the crime.” W. LaFave & A. Scott,
supra,
at 71, 75. Accordingly, in assessing the constitutionality of an affirmative defense, we must inquire whether “the defense is defined in terms of a fact so central to the nature of the offense that, in effect, the prosecution has been freed of the burden” of establishing each constituent element of the crime charged beyond a reasonable doubt.
See id.
§ 2.13, at 233;
accord In re Winship,
Consistent with these principles, two views have emerged concerning the constitutionality of § 1512(c). In
United States v. Kalevas,
The elements of the affirmative defense, the lawful nature of the conduct and the intent to encourage, induce, or cause truthful testimony, are independent facts, proof of which would be sufficient to avoid criminal liability.... The government, to prevail ... must prove the essential ingredients of the crime charged before it may obtain a conviction; thus section 1512(c) meets the demands of the Due Process Clause.
Id. at 1527 (citations omitted).
At least one commentator casts doubt on this reasoning. See Jeffries, supra, at 16-20. He asserts that the government’s burden of proving the elements of § 1512(a), i.e., “that the defendant (i) knowingly (ii) engaged in intimidation, force, threats or misleading conduct (iii) with the intent to influence testimony,” does not require it to prove the nonexistence of the affirmative defense. Id. at 17.
When it enacted § 1512(c), Congress intended it to apply primarily in situations where prosecutors or judges warn a witness of a possible perjury prosecution. See S.Rep. No. 97-532, 98th Cong.2d Sess. 19, reprinted in 1982 U.S.Code Cong. & Ad *753 min.News 2515, 2525 & n. 15. Congress based § 1512(c) on a recommendation in the Final Report of the National Commission on Reform of Federal Criminal Laws § 1321(3)(a) (1971) [“Final Report”]. In the Final Report, however, “existence of the stated circumstance was a defense, not an affirmative defense. Thus the burden would have been on the government to prove its nonexistence.” Jeffries, supra, at 16; see generally Final Report at 114. The legislative history is silent on why Congress modified the Final Report to place the burden of proving the defense on defendants.
The concerns raised in the Jeffries commentary, combined with Supreme Court precedent and established principles of constitutional law, raise doubts concerning the constitutionality of § 1512(c). We need not decide this question, however, because even assuming the statute is unconstitutional, and the court’s jury instruction was erroneous, the constitutional error was harmless beyond a reasonable doubt.
C. Constitutionally Harmless Error
Since concluding that some errors of constitutional dimension could be harmless,
see Chapman v. California,
In
Rose,
the Court resolved a question that had been in doubt since its plurality opinion in
Connecticut v. Johnson,
More recently, in
Burger v. Kemp,
— U.S. -,
Our review of the record demonstrates that the government’s evidence of Clemons’ intent was “so dispositive,”
see Burger,
Although we question whether Clemons ever raised the § 1512(c) defense, we assume for purposes of appeal that he implicitly raised it through scattered cross-examination and obscure references in closing argument. For example, he appeared to defend against the intimidation charge by eliciting on cross-examination that he never directly threatened Dennis’ mother, see App. at 366-67 (Versie Dennis: Clemons never threatened me); see also App. at 376-77 (Versie Dennis’s housemate, David Ervin: Clemons never threatened me). In addition, during his cross-examination of *754 Gregory Dennis, Clemons asked questions attempting to indicate that his threatening remarks to Dennis were in retaliation for having him arrested, not to induce Dennis not to testify truthfully. See, App. at 649 (cross-examination of Gregory Dennis). He also contended that his interest in speaking with Gregory Dennis was to “find out what [was] happening”; not to threaten anyone. See App. at 1877 (closing argument). Finally, we note that Clemons’ counsel acknowledged that his client had requested a § 1512(c) jury instruction even though the record was devoid of any evidence relating to that statutory provision. See App. at 1796-97, 1798.
The government’s evidence, meanwhile, disproves beyond a reasonable doubt that Clemons' conduct was lawful and that his sole intent was to induce Dennis to testify truthfully. After Dennis testified against Clemons before the grand jury, Clemons approached him and stated that: (1) he knew Dennis was scheduled to be a state witness against him; and (2) “his boys” wanted to “do something to [Dennis],” but that Clemons had “played them off, told them that he wasn’t sure if [Dennis] was the one that was supposed to have testified against him or not.” Dennis said he feared Clemons’ boys planned to “beat me up” or “hurt me real bad.” In addition, Dennis testified that Clemons informed him that another potential prosecution witness had already reconsidered her decision to cooperate. At this point, Dennis was so fearful he contacted the state police. The government also established that when Clemons spoke to Dennis’ mother, he made similar threats to harm Dennis. On cross-examination of Dennis and his mother, Clemons never raised the possibility that his statements had been made in an attempt to induce Dennis to testify truthfully, nor, insofar as we can ascertain, did he so argue to either the court or to the jury. Instead, Clemons’ cross-examination elicited only testimony that he never threatened Dennis’ mother or other members of her household.
Thus, the government’s direct evidence of Clemons’ witness intimidation also establishes that the government effectively disproved the defense beyond a reasonable doubt.
12
Even if Clemons’ evidence can be viewed as supporting the § 1512(c) defense, which we seriously doubt, “the predicate facts conclusively established] intent, so that no rational jury could find” that Clemons intended to induce Dennis to testify truthfully.
See Rose,
This is not a case in which the court’s instruction prevented the jury from considering the issue of Clemons’ intent.
See Rose,
For these reasons, the judgment of the district court will be affirmed.
Notes
. Clemons asserts three other claims on appeal: (1) that the government’s immunity grants to others, but not him, violated the equal protection and due process clauses; (2) that he was prejudiced by the delay between sentencing and the district court’s final disposition of his post-trial motions; and (3) that the testimony of the government’s key witnesses was so inherently untrustworthy that the witnesses were incompetent to testify. Clemons’ equal protection/due process and witness competency claims are meritless. We also reject his due process claim of post-trial delays. Although Clemons cites an eighteen-month delay between sentencing and final judgment, some of this delay is attributable to his requests for extensions of time in filing post-trial motions. Moreover, Clemons has failed to demonstrate any prejudice from these delays.
. We have discretion to invoke the concurrent sentence doctrine to "avoid resolution of legal issues affecting less than all of the counts in the indictment where at least one count has been upheld and the sentences are concurrent.”
United States v. Lampley,
*746
The equal protection analysis of the fifth amendment, which governs this case, is identical to that used for the fourteenth amendment.
See Buckley v. Valeo,
. Although
Batson
was not decided at the time of Clemons’ conviction, it applies here because this litigation was not final when the Court decided
Batson. See Griffith v. Kentucky,
We also note that Clemons challenged the government’s conduct as violative of the fifth and sixth amendments. In
Batson,
the court expressly avoided basing its decision on the sixth amendment.
See Batson,
. Indeed, the district court in
United States ex rel Yates
v.
Hardiman,
. Situations may arise where trial judges find it relevant to examine other factors, such as the percentage of the "cognizable racial group” in the jury pool, or the racial composition of the district. We do not envision such inquiries as mandatory. Rather, we are confident that trial judges shall make determinations concerning the relevance of these statistical factors when appropriate.
. The government's proposed per se rule would be particularly pernicious in a district like the Western District of Pennsylvania, which has a relatively low black population. Black defendants would more often than not be forced to forfeit their rights under Batson merely because of the statistical likelihood that their jury ve-nires will be overwhelmingly non-black.
. Compare Roman v. Abrams,
. Section 1512 states in relevant part:
Tampering with a witness, victim, or an informant
(a) Whoever knowingly uses intimidation or physical force, or threatens another person, or attempts to do so, or engages in misleading conduct toward another person, with intent to—
(1) influence the testimony of any person in an official proceeding;
(2) cause or induce any person to— (A) withhold testimony, or withhold a record, document, or other object, from an official proceeding;
shall be fined not more than 5250,000 or imprisoned not more than ten years, or both.
(c) In a prosecution for an offense under this section, it is an affirmative defense, as to which the defendant has the burden of proof by a preponderance of the evidence, that the conduct consisted solely of lawful conduct and that the defendant’s sole intention was to encourage, induce, or cause the other person to testify truthfully.
. With respect to § 1512(a), which sets forth the elements of the offense, the court recited the statutory language, see Supp.App. at 1787, but in its discussion of § 1512(c), the "affirmative defense," the court paraphrased the statute as follows:
It is a defense to ... Count 8, concerning threats and intimidation ... if Oscar Clemons’ conduct toward Greg Dennis consisted solely of lawful conduct, and that Oscar Clemons’ sole intention was to testify truthfully rather than to testify falsely or not at all....
See
Supp.App. at 1794. The court avoided any mention of the statutory requirement concerning a defendant’s burden of proof under § 1512(c).
See id.
Nevertheless, the court expressly refused to charge that the "government has the burden of disproving the [§ 1512(c)] defense by proof beyond a reasonable doubt.”
United States v. Clemons,
. With respect to 1512(c), the court instructed: [I]t is a defense to that count if Oscar Clemons’ conduct toward Greg Dennis consisted solely of lawful conduct, and that Oscar Clemons’ sole intention was to encourage, induce, or cause Greg Dennis to testify truthfully rather than to testify falsely or not at all.
Now, the defendant — I want to emphasize this — the defendant has no duty or burden to advance this defense. His failure to advance or prove such a defense shall not be held against him under any circumstances because, as I said earlier, and I will repeat again for the third, fourth, or fifth or however many times, the defendant has no burden to prove anything. The defendant has no burden to advance any evidence at all. He has no duty to testify.
But, however, if you’re of the belief from all the evidence you heard in this case that Oscar *751 Clemons’ conduct towards Greg Dennis was lawful conduct, that his intention was to encourage, induce or cause Greg Dennis to testify truthfully, you will find the defendant not guilty on that charge....
... So the government always has the burden. Mr. Clemons has no burden of proving anything of any kind. However, if it is proved that his conduct consisted solely of lawful conduct and that his sole intention was to encourage, induce or cause Greg Dennis to testify truthfully, then he would be found not guilty of that charge.
But again I repeat that the defendant has no burden or duty to advance any defenses. He has no duty or burden to testify. He has no duty or burden to put forth witnesses or evidence. He has no duty to testify on his own behalf....
Id. at 1794-95.
. The court’s use of the "if it is proved that" language in describing the requirements of § 1512(c), illustrates the shortcomings of using the passive voice to describe which party bears the burden of proof in a criminal statute. The passive voice is desirable ”[w]hen the agent performing the action is thought of as too unimportant or too obvious to mention and is less significant than the object of the action ... [or] [w]hen the agent performing the action is indefinite or unknown.” See T. Bernstein, The Careful Writer 14-15 (1983); see generally W. Strunk Jr. & E.B. White, The Elements of Style 18 (3d ed.1979). None of those situations apply here.
. Moreover, as we noted above, defendant never raised the § 1512(c) defense until the charging conference. He made no attempt to implicate the defense during trial.
.
But see Hyman v. Aiken,
