The ACLU has taken up the cause of the Denver Three who were ejected from President Bush’s social security event in Colorado last spring. The three have filed a lawsuit in federal court in Denver alleging violation of their civil rights.

The suit identifies the man who ejected them as Michael Casper, a building manager in the General Services Administration in Denver. Casper has worked as a volunteer at several White House events since 1996. The Rocky Mountain News has asked Casper several times if he is the man who forcibly removed the three. He has denied it, made jokes about it and, for some time, avoided being seen and identified by the three. He has acknowledged that he worked the event as a White House volunteer.

ACLU attorney Chris Hansen said the suit is being filed because “the government should not be in the business of silencing Americans who are perceived to be critical of certain policy decisions.”

ACLU spokespersons say this isn’t just about the Denver event:

The lawsuit says that at other presidential appearances around the country, people with views opposing the president’s have been denied entry, ejected or arrested. “This case isn’t about just a couple of people here in Denver,” Silverstein said. “It’s really about a principle, about the rights and liberties of us all.”