Updated

Four Internet users at the center of a legal battle over copyright violations will receive cease-and-desist letters demanding they stop illegally offering free music for downloading, the Recording Industry Association of America (search) said Wednesday.

A U.S. appeals court ruling earlier this month compelled Verizon Communications Inc. (search) to hand over to the association the names of the four subscribers. A spokesman for the RIAA, Jonathan Lamy, declined to identify the subscribers or release copies of the letters.

Lamy said that a fifth person, a customer of Earthlink Inc., also will receive an identical cease-and-desist letter. Earthlink lawyers had balked at identifying their customer to the association until after the recent appeals court ruling.

The RIAA had said previously it hadn't decided how it would proceed against those customers or whether it would identify them publicly.

The association sought the names of the subscribers under the 1998 Digital Millennium Copyright Act (search). It permits music companies to force Internet providers to turn over the names of suspected music pirates upon subpoena from any U.S. District Court clerk's office, without a judge's signature.

Critics of the procedure contend judges ought to be more directly involved, given the potential privacy issues involved when a corporation is asked to reveal personal information about customers over an allegation of wrongdoing.

Verizon has challenged the constitutionality of such copyright subpoenas. Arguments in the appeals court are set for Sept. 16.