 These statutes have been upheld as exercises of Congress 's Commerce Clause power , or in the case of the mail fraud and program bribery statutes , the Postal Clause and the Spending Clause , respectively . In the special case where a member of Congress is the defendant , the Speech or Debate Clause places certain restrictions on the actions that can be prosecuted and proved up . Some commentators have argued that prosecutions of state and local officials under these statutes pose substantial federalism questions , while others argue that the Guarantee Clause provides additional authority for such prosecutions . 
