WASHINGTON, DC — Comcast Corp. acted illegally when it employed file-transfer disruptions to manage traffic on its broadband network, according to a majority of Federal Communications Commission members.Three of five commissioners have signed off on an order censuring Comcast for intentionally slowing or blocking the traffic of customers who used large amounts of bandwidth to transfer files via applications like BitTorrent. Chairman Kevin Martin (a Republican) and commissioners Michael J. Copps and Jonathan S. Adelstein (both democrats) supported the complaint, while Republican Robert M. McDowell said he will vote against the majority and Republican Deborah Tate has not indicated where her vote will fall. The commission as a whole is scheduled to vote officially on Friday.

Although details about the FCC’s ruling will not be available until it is formalized, generally the decision is viewed as affirming the federal government’s right to regulate how internet service providers manage traffic. Analysts said they believe the ruling will send a message that ISPs must disclose traffic-management practices in detail and avoid singling out specific types of traffic for extra scrutiny or action.

“This is a slap on the wrist for Comcast, but it will be a cutting off of the hand for the next provider who violates rules,” IAG Research Senior Vice President Roger Entner told The Washington Post.

In fact, just the FCC’s scrutiny of Comcast encouraged other ISPs to reconsider how they manage network traffic. Since the Comcast inquiry was announced, several broadband providers have moved to regulate their networks by testing variable pricing based on bandwidth usage. Comcast began testing a “tiered pricing” model in early June in Chambersburg, PA, and Warrenton, VA, and Time Warner’s test began in Beaumont, TX, at about the same time. AT&T also has indicated it will evaluate tiered pricing soon.

Comcast also is experimenting in four markets with slowing traffic across the board for the heaviest users without regard to the software applications they employ. It remains to be seen whether the across-the-board-throttling approach will pass muster with the FCC.

Other providers have blocked peer-to-peer file-sharing programs altogether.

“If we didn’t do this, we’d go out of business,” Brett Glass, owner of small ISP Lariat, told the Post. Lariat provides wireless broadband services to the Laramie, WY, area.

Comcast remains adamant that it did nothing wrong in throttling the bandwidth of super-users in order to ensure sufficient pipe space was available for all customers at all hours.

“Our network management practices were reasonable, wholly consistent with industry practices and … we did not block access to Web sites or online applications, including peer-to-peer services,” Comcast spokeswoman Sena Fitzmaurice told the Post.

Commissioners are not expected to fine Comcast.