Whether, under current Rule 12, after a defendant has made a timely motion to suppress evidence that did not include a particular argument, should the court of appeals review that argument for plain error under Rule 52, without requiring any special good-cause showing—the rule in four circuits—or must the defendant first prove good cause to the court of appeals—as in the Tenth Circuit and four other circuits?

Whether the court of appeals should review an untimely suppression argument for plain error under Rule 52 or require a showing of good cause