On Tuesday, the RIAA asked a federal judge in Washington, D.C., for an order compelling Verizon Communications to reveal the name of a customer accused of illegally trading hundreds of songs. Citing privacy concerns and potential legal liability, Verizon has refused to comply with a subpoena the RIAA sent last month.

"It's not that they don't want to turn over the name," said Mitch Glazier, an RIAA senior vice president. "It's that they don't want to be liable for turning over a subscriber's name."

Until now, the entertainment industry has relied on civil lawsuits aimed at corporations, not individuals, to limit widespread copyright infringement on peer-to-peer networks. Now, however, the RIAA is revising its strategy and appears ready to sue individuals swapping songs over the Internet.

At issue in the RIAA's request is an obscure part of the Digital Millennium Copyright Act (DMCA) that permits a copyright owner to send a subpoena ordering a "service provider" to turn over information about a subscriber. It is not necessary to file a lawsuit to take advantage of the DMCA's expedited subpoena process.

Verizon says it complies with requests regarding material that customers store on its servers. But because these allegedly illicit files reside on a peer-to-peer node, the company says, this is a novel situation, and a DMCA subpoena is not sufficient.

"Verizon looked carefully at the subpoena. This is different from anything they had sent us in the past," said Sarah Deutsch, a vice president at the telecommunications company.

"It created a very difficult policy issue for us," Deutsch said. "We understand that RIAA has a problem and needs this information. At the same time, we have an equally legitimate concern that they comply with the proper legal process."

RIAA's Glazier said, "We believe the (DMCA) subpoena process applies." The DMCA defines service provider to mean "a provider of online services or network access."

The RIAA has not yet decided how to proceed with civil suits against individuals. "It's definitely on the table," Glazier said.

Also on Tuesday, a Justice Department official said the government was prepared to begin prosecuting alleged peer-to-peer pirates. A few weeks ago, some of the most senior members of Congress pressured the Justice Department to invoke a little-known law, the No Electronic Theft Act, against peer-to-peer users who swap files without permission.