By Eriq Gardner

Comcast is suing the Federal Communications Commission, challenging the government agency's authority to enforce a policy statement relating to the regulation of how ISPs thwart customers using peer-to-peer networks.
Last August,
FCC chairman Kevin Martin came down hard on Comcast after the company took steps to delay or block subscriber downloads and uploads of movies, TV shows, and music. At the time, Comcast argued the need to clamp down on customer usage of P2P applications because they were causing congestion on the network. In response, the FCC wondered whether Comcast's real motivation was in protecting the cable television industry from potential online competitive threats.
"Would it be OK if the post office opened your mail, decided they didn't want to bother delivering it, and hid that fact by sending it back to you stamped 'address unknown — return to sender'?" wrote Martin in a
opinion that ordered Comcast to stop being a traffic cop.
Now, about a year after Martin delivered his rebuke, Comcast sends the FCC its own challenge, saying in an opening brief to D.C. Appeals Court that the agency is basically inventing federal Internet policy without authority.
"For the FCC to conclude that an entity has acted in violation of federal law and to take enforcement action for such a violation, there must have been 'law' to violate," says the
Opening Brief. "Here, no such law existed."
Comcast is being supported in this action by NBC Universal, the National Cable and Telecommunications Association, and Qwest Communications International, who are appearing as intervenors.
UPDATE: Previously, we wrote that Comcast was challenging the government agency's authority to regulate how ISPs thwart customers using peer-to-peer networks. Comcast clarifies they are not disputing the agency's authority to regulate in this area if it chooses, but rather the enforceability of its policy statement and whether the FCC went through the proper channels to establish regulations.