Looks like Cindy Sheehan was arrested in the U.S. Capitol for nothing other than political expression.  

CNN.com Report

WASHINGTON (CNN) -- Peace activist Cindy Sheehan was arrested Tuesday in the House gallery after refusing to cover up a T-shirt bearing an anti-war slogan before President Bush's State of the Union address.

According to a blog post on Michael Moore's Web site attributed to Sheehan, the T-shirt said, "2,245 Dead. How many more?" -- a reference to the number of U.S. troops killed in Iraq.

"She was asked to cover it up. She did not," said Sgt. Kimberly Schneider, U.S. Capitol Police spokeswoman.

Schneider said Sheehan was arrested around 8:30 p.m. on charges of unlawful conduct, a misdemeanor that carries a maximum penalty of a year in jail.

Is this not a foursquare violation of the First Amendment in our seat of government?  She was there with a ticket.  According to WaPo:  

Sheehan, who was apparently given a gallery ticket by a member of Congress, began to attract notice about 30 minutes to an hour before President Bush's State of the Union speech.  

Sheehan, whose son was killed in Iraq, opened her jacket to reveal a T-shirt that, according to a supporter, gave the number of U.S. war dead and asked, "How many more?"

She was also vocal, said U.S. Capitol Police Chief Terrance W. Gainer, and after she ignored instructions to close her jacket and quiet down, she was led out and arrested. Demonstrating in the House gallery is prohibited.

Yeah, if a government officer told me to cover up my t-shirt at a political event, I'd be vocal, too.