The lawsuit involves a 3-2 decision the FCC handed down in early August that found Comcast’s practices violated so-called net-neutrality principles, and ordered the company to provide more details of its network-management policies within 30 days. The FCC also ordered Comcast to stop by the end of the year blocking traffic related to specific applications, such as file-sharing software that allows users to swap videos.

It was the first time the FCC had found a company in violation of the commission’s net-neutrality principles, which lay out consumers’ Internet rights.

Comcast was widely expected to appeal the FCC’s decision, even though the company wasn’t fined. Comcast says its practice of sometimes slowing Internet traffic on file-sharing networks like BitTorrent is reasonable and necessary to prevent a few heavy bandwidth users from slowing other customers’ service. The lawsuit, filed in the U.S. Court of Appeals here, doesn’t go into details about the complaint, but company officials have argued that the FCC has authority to bring enforcement actions under formal rules, not principles. While the FCC has stated a position on net neutrality, it hasn’t established formal rules.

Read the full story in ‘The Wall Street Journal’ here.