"Twinkie defense" is a derisive label for an improbable legal defense. It is not a recognized legal defense in jurisprudence, but a catch-all term coined by reporters during their coverage of the trial of defendant Dan White for the murders of San Francisco city Supervisor Harvey Milk and Mayor George Moscone. White's defense was that he suffered diminished capacity as a result of his depression, a symptom of which was a change in diet from healthy food to Twinkies and other sugary foods. Contrary to common belief, White's attorneys did not argue that the Twinkies were the cause of White's actions, but that their consumption was symptomatic of his underlying depression. The product itself was only mentioned in passing during the trial. White was convicted of voluntary manslaughter rather than first-degree murder, and served five years in prison.

Daniel James White was an American politician who assassinated George Moscone, the mayor of San Francisco, and Harvey Milk, a member of the San Francisco Board of Supervisors, inside City Hall on November 27, 1978. White was convicted of manslaughter for the deaths of Milk and Moscone and served five years of a seven-year prison sentence. Less than two years after his release, he returned to San Francisco and later committed suicide.