Annotation 4 - Article VI
Congress may require no other oath of fidelity to the Constitution, but it may superadd to this oath such other oath of office as its wisdom may require. 161 It may not, however, prescribe a test oath as a qualification for holding office, such an act being in effect an ex post facto law, 162 and the same rule holds in the case of the States. 163
[Footnote 163] Cummings v. Missouri, 71 U.S. (4 Wall.) 277, 323 (1867). See also Bond v. Floyd, 385 U.S. 116 (1966), where the Supreme Court held that antiwar statements made by a newly elected member of the Georgia House of Representatives were not inconsistent with the oath of office, pledging support to the federal Constitution.