Capitol police dropped charges of unlawful conduct against antiwar activist Sheehan, and apologized to her and Young, the wife of Rep. C.W. Bill Young of Florida, saying "wearing a T-shirt is not enough reason to be asked to leave the gallery, or be removed from the gallery, or be arrested," according to the Associated Press.
But Young's dismissal and Sheehan's arrest were not about their fashion or their freedom of speech, they were about appropriate behavior, some say.
"If these people were wearing these shirts to a ball game or the supermarket, no one would have cared and it would not be inappropriate," says Tim O'Brien, of the media relations consulting firm O'Brien Communications in Pittsburgh. "But the State of the Union Address is an official invitation-only state event. As a closed event, those who attend have to abide by the rules or guidelines of their hosts, in this case the federal government."
Sheehan's T-shirt said: "2245 Dead. How many more?" Young's was emblazoned with a more patriotic statement: "Support the Troops - Defending Our Freedom."
Some observers decried the women's ejection, even after the Capitol police's apology.
"I think one of the things that's interesting is that there is no policy," said Michael Meyerson, constitutional law professor at the University of Baltimore School of Law. "It felt very much that it was at the discretion of the police or ... the people in charge of the police as to who could stay or who could go. ... That makes me nervous."
Sheehan and Young are not the first to wear their thoughts on their chests.
For centuries, people have used fashion to express themselves. An exhibit called Wearing Propaganda, currently at the Bard Graduate Center for Studies in the Decorative Arts, Design and Culture in New York, highlights the political imagery in linings of Japanese kimonos during the 1930s and scarves worn by American women that read, "Remember Pearl Harbor."
"In times of war, propaganda appears everywhere, even places we don't necessarily consider as vehicles of propaganda," says Jacqueline Atkins, a curator at the Allentown Art Museum in Pennsylvania, where the exhibit will be in October.
Broadcasting political beliefs through fashion choices is a popular tactic even today. In malls and shops, clothing with sayings that espouse a political belief or promote a social or civic cause has been gaining popularity - especially because of the war in Iraq and the sluggish economy.
One such shirt promoted on the Web site T-ShirtHumor.com says, "Veto Alito." Another says, "Don't blame me. I voted for Gary Coleman."
"I can tell you that the trend of wearing your political opinions is an ever-growing one. Our business has tripled over the past three years," says Anthony Phipps, communications director for T-ShirtHumor.com.
Phipps said he found Sheehan's and Young's ejection from the House of Representatives "disturbing."
"In America we demand an open marketplace of ideas, and the ideas being expressed on T-shirts are just as protected as those printed on a page," he said.
Still, says Meyerson, even with the First Amendment duly considered, "if you're asking if it was good manners, probably not."