A federal judge ruled yesterday that the Port Authority unlawfully discriminated against a nonprofit group by refusing to accept its advertisements designed to inform the public that ex-felons in Pennsylvania have the right to vote.

U.S. District Judge Terrence F. McVerry ruled that the authority engaged in "viewpoint discrimination" in refusing to sell ad space on buses to the Pittsburgh League of Young Voters Education Fund.

The league, joined by the American Civil Liberties Union of Pennsylvania, sued the authority in 2006.

The authority's advertising policy, in place since 1998, said that the agency would not run noncommercial or political ads.

In a 38-page ruling, Judge McVerry roundly dismissed the authority's claim that it rejected the voting rights ads because they did not offer any commercial service. He called the policy "a pretext for viewpoint discrimination."

"The testimony and evidence presented at trial clearly demonstrated that the defendants accepted numerous advertisements for display on Port Authority vehicles which had content similar to plaintiffs' proposed advertisement and which were not truly commercial in nature," he wrote.

He said the authority accepted numerous ads "designed to educate bus riders about their rights and the rights of others, including advertisements about the rights of young women, the right of low-income people to tax credits, the right of dogs to be free from abuse, and the right of people to be free from housing discrimination."

The judge barred the authority from rejecting the group's ads.

Sara Rose, ACLU staff attorney, said the organization was "thrilled" by the ruling.

She said there is considerable misinformation about the voting rights of those convicted of crimes. "We thought the buses would be a great way to reach people to educate them about this issue."

Judge McVerry awarded $1,061 in damages to the ACLU and $820 to the league for their need to divert staff from other tasks because of the authority's refusal to accept the ads. But that is a fraction of the cost of the case to the financially strapped transit agency.

The authority had spent at least $89,000 on outside legal counsel to fight the lawsuit before it went to trial in December, and Judge McVerry's ruling invites the ACLU to petition for counsel fees, costs and expenses.

"I'm sure it will be at least six figures since we had to go to trial," Ms. Rose said.

Port Authority officials were reviewing the ruling late yesterday and had no immediate comment, spokesman Jim Ritchie said.