Marilyn J. Mosby v. United States

Federal law subjects millions of Americans each year to potential criminal liability for statements made on government forms containing undefined statutory and regulatory terminology. Most courts of appeals, consistent with Bronston v. United States, 409 U.S. 352 (1973), and the Due Process Clause, hold that a perjury conviction cannot rest on an answer to a question whose meaning reasonable persons of ordinary intellect could not ascertain at the time it was asked. The Fourth Circuit departed from that rule, concluding that ambiguity may be cured by a district court's post-hoc definition supplied years after the statement was made. The question presented is: Whether, in a prosecution for perjury under 18 U.S.C. § 1621, courts must determine whether the challenged question had a meaning upon which reasonable persons of ordinary intellect could agree at the time the defendant answered it, or whether a conviction may instead be sustained based on a definition first supplied by a court after the fact. -i-