- The Full Faith and Credit Clause provides that "full faith and credit shall be given in each state to the public acts, records, and judicial proceedings of every other state." Critics argue that Congress exceeded its proper authority under the Constitution by enacting DOMA.
- The Equal Protection Clause guarantees that similarly situated persons will be treated alike. Critics of DOMA argue that the legislation illegally discriminates against homosexual couples.
- The Due Process Clause protects certain fundamental rights, including the right to enter into a marriage relationship. Those opposed to DOMA argue that the law violates this fundamental right by unreasonably restricting the liberty of same-sex couples.
However, the likelihood of the ratification of such an amendment is unlikely, at best. In fact, the Constitution has only been amended 27 times since it was adopted in 1787. Further, in order to amend the Constitution, a two-thirds majority is required in both chambers of Congress (i.e., 290 votes in the House and 67 votes in the Senate), and the amendment must be ratified by at least 38 states.