Plain error is an error declared by an appellate court to be patently obvious in a lower court decision or action and causes a reversal. When a defendant raises an issue on appeal that was not raised before the judge, the court of appeals may review for plain error. Federal procedural rules define plain error as a highly prejudicial error affecting substantial rights.
The appellant has the burden to show plain error, which is error that is clear or obvious and that materially prejudices the substantial rights of appellant; once appellant has met his burden of persuasion, the burden shifts to the government to show that the error was not prejudicial. To be plain error: (1) there must be an error; (2) the error must be plain (clear or obvious); and (3) the error must materially prejudice the substantial rights of the defendant).