Legal Definitions - perjury-trap doctrine

The perjury-trap doctrine is a legal principle that prevents prosecutors from intentionally using a grand jury proceeding to create a perjury charge against a witness. This doctrine applies when a prosecutor calls someone to testify before a grand jury, not primarily to gather information relevant to an ongoing investigation, but rather with the specific intent of eliciting false statements from that person, which can then be used as the basis for a perjury indictment. If a court determines that a perjury charge resulted from such a "trap," the indictment must be dismissed.

Here are some examples illustrating the perjury-trap doctrine:

• Example 1: Irrelevant Questioning

  A grand jury is investigating a large-scale corporate fraud scheme. The prosecutor calls a low-level administrative assistant, Ms. Chen, to testify. Ms. Chen is not suspected of involvement in the fraud. Instead of asking her about the corporate fraud, the prosecutor spends the entire session asking highly detailed questions about Ms. Chen's personal travel expenses from three years ago, which are completely unrelated to the fraud investigation. The prosecutor knows Ms. Chen has a poor memory for dates and figures and suspects she might misstate minor details under oath.

  How this illustrates the doctrine: The prosecutor's primary goal in questioning Ms. Chen about her personal travel expenses was not to gather evidence for the corporate fraud investigation. Instead, the questioning was designed to induce her to make a false statement about an immaterial matter, thereby creating a perjury charge. If Ms. Chen were subsequently charged with perjury based on this testimony, the perjury-trap doctrine could lead to the dismissal of that charge.

• Example 2: Pretextual Investigation

  A prosecutor suspects Mr. Davis of having lied on a previous loan application to a bank, but has insufficient evidence to charge him with bank fraud. The prosecutor then convenes a grand jury to investigate a minor, unrelated instance of alleged public corruption involving a local zoning board. The prosecutor calls Mr. Davis to testify before this grand jury. During his testimony, instead of asking about the zoning board corruption, the prosecutor focuses intensely on the details of Mr. Davis's past loan application, hoping he will repeat the alleged false statements under oath.

  How this illustrates the doctrine: The grand jury's actual investigation was into public corruption, not Mr. Davis's loan application. The prosecutor used the grand jury's authority as a pretext to compel Mr. Davis's testimony on an unrelated matter, with the specific intent of securing a perjury charge. If a perjury indictment resulted from this line of questioning, the perjury-trap doctrine would likely apply, leading to dismissal.

• Example 3: Fishing for Falsehoods

  A grand jury is investigating a complex drug trafficking ring. The prosecutor believes Mr. Kim is involved but lacks sufficient evidence to indict him for drug offenses. The prosecutor calls Mr. Kim to testify. During his testimony, the prosecutor asks Mr. Kim a series of highly specific questions about a minor social gathering he attended two years prior, which has very little direct relevance to the drug trafficking investigation. The prosecutor has prior information suggesting Mr. Kim has previously given inconsistent accounts of this gathering to informal investigators.

  How this illustrates the doctrine: The prosecutor's questioning about the minor social gathering was not genuinely aimed at uncovering information material to the drug trafficking ring. Instead, it was a deliberate attempt to exploit Mr. Kim's potential memory lapses or prior inconsistencies to elicit a false statement under oath, thereby creating a perjury charge that would be easier to prove than the drug offenses. This scenario exemplifies a perjury trap, and any resulting perjury indictment would be vulnerable to dismissal under this doctrine.