Actual malice in US law is defined as "knowledge that the information was false" or that it was published "with reckless disregard of whether it was false or not." This is only the definition in the United States and came from the landmark 1964 lawsuit New York Times Co. v. Sullivan that ruled that public officials needed to prove actual malice in order to recover damages for libel.

This term was not newly invented for the Sullivan case, but was a term from existing libel law. In many jurisdictions proof of "actual malice" was required in order for punitive damages to be awarded, or for other increased penalties. Since proof of the writer's malicious intentions is hard to provide, proof that the writer knowingly published a falshood was generally accepted as proof of malice, under the assumption that only a malicious person would knowingly publish a falshood. In the Sullivan case the Supreme Court adopted this term and gave it constitutional significance, at the same time defining it in tems of the proof which had previously been usual.

Actual malice is different from common law malice which indicates spite or ill-will.