Article I, Section 10, Clause 1:
No State shall enter into any Treaty, Alliance, or Confederation; grant Letters of Marque and Reprisal; coin Money; emit Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing the Obligation of Contracts, or grant any Title of Nobility.
Statutes passed after the Civil War with the intent and result of excluding persons who had aided the Confederacy from following certain callings, by the device of requiring them to take an oath that they had never given such aid, were held invalid as being bills of attainder, as well as ex post facto laws.1
Other attempts to raise bill-of-attainder claims have been unsuccessful. A Court majority denied that a municipal ordinance that required all employees to execute oaths that they had never been affiliated with Communist or similar organizations, violated the clause, on the grounds that the ordinance merely provided standards of qualifications and eligibility for employment.2 A law that prohibited any person convicted of a felony and not subsequently pardoned from holding office in a waterfront union was not a bill of attainder because the
distinguishing feature of a bill of attainder is the substitution of a legislative for a judicial determination of guilt and the prohibition
embodies no further implications of appellant's guilt than are contained in his 1920 judicial conviction.3