(The NAACP billboard that is the subject of a lawsuit against the City of Philadelphia. Image provided)

PHILADELPHIA (CBS) – The NAACP and the ACLU have filed a federal lawsuit against the City of Philadelphia and the company that handles its advertising at the airport, over the rejection of an airport ad promoting criminal justice reform.

The NAACP’s ad highlighting the nation’s high incarceration rate says, “Welcome to America, home to 5% of the world’s people and 25% of the world’s prisoners. Let’s build a better America together.”

Mary-Catherine Roper, staff attorney for the ACLU of Philadelphia, says the city, which owns the airport, turned down the ad.

“At the time they didn’t say why, but later the city said that they have a policy of not allowing advocacy advertising,” Roper tells KYW Newsradio.

But she says the airport has allowed issue ads for causes like the World Wildlife Fund, and research into cancer and other diseases.

“We think that this advertisement was rejected because it was seen as controversial, and that is just not the kind of censorship that the government should be engaged in,” Roper says.

And that, she says, is a violation of the First Amendment.

A spokesman for Mayor Nutter’s administration said they can’t comment on pending litigation.

Reported by Molly Daly, KYW Newsradio 1060