The ACLU filed a lawsuit on behalf of The Center for Investigative Reporting challenging the Philadelphia-area transit system’s advertising restrictions as violations of the First Amendment. The free speech lawsuit follows the agency’s rejection of ads from CIR about its reporting on racial discrimination in the housing market.

CIR’s proposed ad would feature an informative graphic showcasing public data its reporters collected and analyzed that found racial disparities in the conventional home mortgage market in 61 metro areas across America, including in Philadelphia. CIR’s news investigation prompted the Pennsylvania attorney general to probe racial discrimination in Philadelphians’ access to home loans.

The Southeastern Pennsylvania Transportation Authority said that it refused to run the ad on its buses and trains because SEPTA policy prohibits ads with “political” content, defined broadly to include anything that relates to government policies, and ads that take a position on “matters of public debate.”

The lawsuit argues that both of these prohibitions violate free speech rights guaranteed by the Constitution. The suit asks the court to declare those provisions unconstitutional and to order SEPTA to run CIR’s ads.

The challenged provisions of SEPTA’s advertising standards violate the free speech clause of the First Amendment in several ways. The provisions in the SEPTA policy are vaguely defined, giving SEPTA unfettered discretion to censor a broad range of speech. They also discriminate based on viewpoint by censoring controversial speech.

The Supreme Court has rejected the notion that the government has a legitimate interest in censoring political speech or speech it finds offensive. Debate on public issues is the cornerstone of participatory democracy, and no government entity, including SEPTA, should single it out for censorship.