Occasionally, a witness will try to mislead the inquiry by giving answers to questions that, although literally true, are evasive or unresponsive. In Bronston v. United States, 409 U.S. 352 (1973), the United States Supreme Court unanimously held that such conduct does not violate 18 U.S.C. § 1621, reasoning that "if a witness evades, it is the lawyer's responsibility to recognize the evasion and to bring the witness back to the mark, to flush out the whole truth with the tools of adversary examination." Id. at 358-59. Thus, the jury does not focus on whether the statement was intended to mislead or divert the examination, but rather considers whether the declarant "does not believe his answer to be true." Id. at 359. See also, United States v. Debrow, 346 U.S. 374, 376 (1953).
Answers to ambiguous questions similarly cannot support perjury prosecutions, particularly if it is unreasonable to expect the defendant to understand the question posed. United States v. Heater, 63 F.3d 311, 327 (4th Cir. 1995)(conviction affirmed; compound question found intelligible), cert. denied, 116 S.Ct. 796 (1996); United States v. Dean, 55 F.3d 640, 661 (D.C. Cir. 1994)(conviction reversed), cert. denied, 116 S.Ct. 1288 (1996); United States v. Reilly, 33 F.3d 1396, 1416 (7th Cir. 1994)(conviction affirmed); United States v. Boone, 951 F.2d 1526, 1534 (9th Cir. 1991)(conviction affirmed); United States v. Ryan, 828 F.2d 1010, 1015 (3d Cir. 1987). Courts have distinguished Bronston by considering the context of the defendant's evasive replies. United States v. Bryan, 58 F.3d 933, 960 (4th Cir. 1995)(the government's repeated inquiries at the previous trial provided sufficient notice to the defendant as to the broader focus of the questioning); United States v. Abroms, 947 F.2d 1241, 1245 (5th Cir. 1991)("an answer that is responsive and false on its face does not come within Bronston's literal truth analysis simply because the defendant can postulate unstated premises of the question that would make his answer literally true"), cert. denied, 505 U.S. 1204 (1992).
Witnesses who claim not to remember, rather than deny a fact, may be prosecuted for perjury. However, the government must prove both that the witness at one time knew the fact and that the witness must have remembered it at the time he or she testified. United States v. Chen, 933 F.2d 793, 795 (9th Cir. 1991). If the dates of the transaction and testimony are sufficiently close, memory may be inferred. Instances in which the witness remembered other events that occurred at the same time or earlier than the event in question, or mentioned the event either immediately before or after his testimony, would be probative of the witness's memory at the time of the testimony. The two witness rule does not apply to prosecutions based on false memory lapses, and circumstantial evidence is sufficient, since there is no direct evidence possible concerning what the defendant actually believed. Gebhard v. United States, 422 F.2d 281, 287 (9th Cir. 1970).