United States v. Webster

At Clinton Webster's (defendant) bank-robbery-aiding-and-abetting trial, the government called the actual robber, King, whose testimony unexpectedly exonerated Webster. To impeach King, the prosecutor introduced his earlier statements to the FBI implicating Webster, and the judge instructed the jury to consider those statements only for impeachment, not as substantive proof of guilt. Webster was convicted and appealed, arguing the government should not have been allowed to impeach its own witness this way absent genuine surprise.