Thailand's Constitutional Court ruled unanimously Tuesday that Prime Minister Samak Sundaravej violated the constitution by appearing on a TV cooking show while in office, and must resign.
The nine-member court said the cabinet must also step down but could stay on as a caretaker government for 30 days. One of the cabinet members is expected to take over as caretaker prime minister until Mr. Samak's People Power Party votes for a new leader.
The ruling does not ban Mr. Samak from politics, and his party immediately said it would re-elect him as prime minister.
There has been no reaction yet from Mr. Samak.
Mr. Samak's troubles run far deeper than involvement with a cooking show. His critics accuse him of being a puppet of former Prime Minister Thaksin Shinawatra, who was deposed by the military amid corruption allegations in 2006.
Thousands of protesters have surrounded a government compound in Bangkok for the past two weeks, demanding Mr. Samak's resignation.
They greeted news of today's ruling with cheers -- but vowed to remain on the grounds until he steps down.
Mr. Samak had argued in court that he had been hired to do the shows, but was not an employee of the producers. It is illegal under the Thai constitution for a prime minister to work for a private company.
Before assuming the office of prime minister, Mr. Samak hosted the show, called "Tasting and Complaining." But after becoming prime minister he left that role, returning only for guest spots.