The process of nullification may refer to:

• The Hartford Convention, in which New England Federalists considered secession from the United States of America. (See also: interposition)
• The Nullification Crisis in the United States of America, in which South Carolina passed legislation legalizing its invalidation of objectionable federal laws.
• Jury nullification, a legal term that refers to a jury's right to deliver a verdict in contradiction to written law.
• Body nullification, the practice of removing body parts.