A judge for the U.S. District Court for the District of Columbia dismissed a 2010 age discrimination lawsuit against the U.S. Capitol Police on Tuesday.

The genesis of the suit dates to September 2009, when the Library of Congress police department merged with the Capitol Police.

At the time, the department had no mandatory retirement age and most of the library’s force of about 100 officers were black and older than 40. The terms of the merger adopted the Capitol Police policy that officers must step down from police duty at the age of 57, either by retiring or by moving to a civilian position within the department.

The decision sparked a number of complaints and lawsuits, including the case dismissed Tuesday. In Porter et al v. the United States Capitol Police Board, nine former Library of Congress police officers sued for $300,000 each after being moved to civilian jobs after the merger. Some of them retired rather than take the new roles, and they argued that the move amounted to age discrimination. They also contended that the merger agreement was unconstitutional because it discriminated against the Library’s black officers by transferring them to civilian posts.

In dismissing the case, Judge James Boasberg found that the terms of the merger made clear that there would be an age limit for police duty. He also said there was no indication that the agreement contained language that expressly discriminated against African-Americans and that the plaintiffs could not prove that racism was a factor.

The plaintiffs’ attorney, Jimmy A. Bell, said Wednesday that he and his clients plan to explore an appeal.

“This is sad day for all Americans when age alone, not experience or ability to do the job, can determine your ability to work,” Bell said.