Pe ioner Walter L. Nixon, Jr., asks this Court to decide whether Senate Rule XI, which allows a committee of Senators to hear evidence against an individual who has been impeached and to report that evidence to the full Senate, violates the Impeachment Trial Clause, Art. I, § 3, cl. 6. That Clause provides that the "Senate shall have the sole Power to try all Impeachments." But before we reach the merits of such a claim, we must decide whether it is "justiciable," that is, whether it is a claim that may be resolved by the courts. We conclude that it is not.