Mason v. United States

Mason had challenged the government’s late disclosure of evidence and the refusal to separate his trial from a co-defendant’s trial; the denial did not decide those claims on the merits.

In his petition, Mason argued that a key witness had reportedly written a letter describing plans to lie against the other defendant, and that the government disclosed it too late. He also argued that a juror’s written note showed unfair spillover from the joint trial.

The case reached the Supreme Court through a petition asking it to review a ruling from the United States Court of Appeals for the District of Columbia Circuit.