Posted at 9:37 and updated with a copy of the lawsuit.

King County violated the Constitution when it accepted money to run ads on the side of Metro buses but then refused to post them when they proved controversial, according to a lawsuit today filed by the ACLU of Washington. Purchased by the Seattle Mideast Awareness Campaign, the ads criticized "Israeli War Crimes" and were set to run in late December.

"King County’s decision to not publish Plaintiff SeaMAC’s ad, as promised, violates the First Amendment of the United States Constitution (which is made applicable to state entities through the Fourteenth Amendment) as applied," says the complain filed in US District Court of Western Washington. "Defendant King County’s apparent reliance on its Advertising Policy and/or its Contract for Advertising, as justification for its change of position, violated the First Amendment of the United States Constitution (which is made applicable to the state entities through the Fourteenth Amendment) as applied and on its face."

Here's the six-page lawsuit.

The hubbub bubbled up when King County Council member Peter von Reichbauer complained that the ads would incite anti-Semitic violence and people called the county by the hundreds to voice outrage. On December 23, King County executive Dow Constantine announced the ads would be banned and he placed a 30 day moratorium on all non-commercial bus advertisement.

"We welcome the opportunity for the court to clarify the standards governing Metro's ability to regulate ads on its buses," said Frank Abe, spokesman for County Executive Constantine, when asked about the lawsuit this morning.

"They've changed their policy after accepting ad revenue and are now retroactively applying this new policy," the group's executive director, Kathleen Taylor, told The Stranger last month. Also at issue are First Amendment questions about banning certain types of free speech, simply by virtue of it being political or controversial.

The ACLU, which is holding a 10:30 a.m. news conference, will release a copy of the lawsuit later today.