For the last 15 years, Internet service providers have acted - to use an old cliche - as wide-open information super-highways, letting data flow uninterrupted and unimpeded between users and the Internet.

But I.S.P.’s may be about to embrace a new metaphor: traffic cop.

At a small panel discussion about digital piracy at NBC’s booth on the Consumer Electronics Show floor, representatives from NBC, Microsoft, several digital filtering companies and the telecom giant AT&T said discussed whether the time was right to start filtering for copyrighted content at the network level.

Such filtering for pirated material already occurs on sites like YouTube and Microsoft’s Soapbox, and on some university networks.

Network-level filtering means your Internet service provider – Comcast, AT&T, EarthLink, or whoever you send that monthly check to – could soon start sniffing your digital packets, looking for material that infringes on someone’s copyright.

“What we are already doing to address piracy hasn’t been working. There’s no secret there,” said James Cicconi, senior vice president, external & legal affairs for AT&T.

Mr. Cicconi said that AT&T has been talking to technology companies, and members of the M.P.A.A. and R.I.A.A., for the last six months about carrying out digital fingerprinting techniques on the network level.

“We are very interested in a technology based solution and we think a network-based solution is the optimal way to approach this,” he said. “We recognize we are not there yet but there are a lot of promising technologies. But we are having an open discussion with a number of content companies, including NBC Universal, to try to explore various technologies that are out there.”

Internet civil rights organizations oppose network-level filtering, arguing that it amounts to Big Brother monitoring of free speech, and that such filtering could block the use of material that may fall under fair-use legal provisions — uses like parody, which enrich our culture.

Rick Cotton, the general counsel of NBC Universal, who has led the company’s fights against companies like YouTube for the last three years, clearly doesn’t have much tolerance for that line of thinking.

“The volume of peer-to-peer traffic online, dominated by copyrighted materials, is overwhelming. That clearly should not be an acceptable, continuing status,” he said. “The question is how we collectively collaborate to address this.”

I asked the panelists how they would respond to objections from their customers over network level filtering – for example, the kind of angry outcry Comcast saw last year, when it was accused of clamping down on BitTorrent traffic on its network.

“Whatever we do has to pass muster with consumers and with policy standards. There is going to be a spotlight on it,” said Mr. Cicconi of AT&T.

After the session, he told me that I.S.P.’s like AT&T would have to handle such network filtering delicately, and do more than just stop an upload dead in its tracks, or send a legalistic cease and desist form letter to a customer. “We’ve got to figure out a friendly way to do it, there’s no doubt about it,” he said.