Unsworn recantation. The Second Circuit in Haouari v. United States denied without prejudice a criminal convict's motion to file a second motion under 28 U.S.C. 2255 because the new evidence was not in the proper form. The evidence was an unsworn letter from the petitioner's co-conspirator, recanting his prior testimony. The Court held that the evidence would have to be provided in the form of a sworn affidavit.

The decision can be found here.