TV stations are asking a federal court to put a stop to the FCC’s plans to require that TV broadcasters post political ad spending information online.

The new rule initially would apply to network affiliates in the top 50 markets, and is scheduled to take effect on Aug. 2.

In a filing with the U.S. District Court of Appeals on Tuesday, the National Assn. of Broadcasters asked for an emergency stay and said that the FCC engaged in “arbitrary and capricious decision making” when it adopted the new rule in late April. Although broadcasters already are required to make such information public, it usually only can be accessed by visiting the station itself and requesting the public file.

“This will place NAB’s members at a distinct disadvantage to their non-broadcast competitors, who will not be required to post rate information on the Internet,” the NAB said. They also said that the stations would face a “significant burden” by being forced to post information online “on an almost real-time basis.”

The NAB also said that the new rule raises antitrust concerns, as stations will now have easy access to a competitor’s rate information. Although the NAB proposed a compromise proposal to offer a summary of ad buys without the rate information, a majority of the FCC’s commissioners rejected it.

“Non-broadcast competitors will be able to determine in a matter of seconds exactly what prices local broadcast stations are charging for specific spots,” the NAB said. “As a result, they will acquire an unfair advantage over broadcasters in the competition for political and commercial advertising, just as a poker player who is able to peak at an opponent’s hand acquires an unfair advantage in a poker game.”

FCC chairman Julius Genachowski, a champion of the new rule, told lawmakers on Capitol Hill on Tuesday that it can be carried out with relative ease and that the agency would hold a demonstration workshop next week. The data will be posted to a central database on the FCC’s website. He was addressing an oversight hearing of a House Energy and Commerce subcommittee hearing.