WASHINGTON -- The U.S. Supreme Court, which bans cameras and cell phones from its proceedings, yesterday heard arguments about the legal status of even more exotic innovations -- cable modems and Internet programs that allow computer users to download copyrighted music.

In the first argument yesterday, an entertainment industry lawyer -- supported by the Bush administration -- asked the justices to rule that Internet file-sharing services like Grokster and StreamCast can be sued because their subscribers download copyrighted songs and video files.

In the second case, the cable television industry, which increasingly offers Internet services, sought to uphold a Federal Communications Commission ruling exempting them from regulations imposed on phone firms.

In questioning in both cases, the justices seemed reluctant to impose limits on new communications services that Congress hasn't insisted upon.

A lawyer for MGM Studios and other entertainment firms argued that creators of "peer-to-peer" file-sharing programs like Grokster encourage "massive" copyright infringement.

Donald B. Verrilli said at least 90 percent of files downloaded by computer users are protected by copyright. "There are 26 billion unlawful downloads every month," he said.

Suggesting grounds on which a ruling in Grokster's favor by the 9th U.S. Circuit Court of Appeals in San Francisco might be reversed, he said file-sharing services "actively induce" subscribers to infringe copyrights.

But Richard G. Taranto, a lawyer for file-sharing services, pleaded with the court not to engage in "overkill" by hobbling a product with "a large and growing legitimate use," including downloading songs in the public domain and others whose creators willingly allow free distribution.

Several justices worried that a decision clamping down on Grokster would stifle innovation.

In yesterday's second argument, lawyers for the cable TV industry and the Bush administration urged the court to restore a 2002 FCC decision that broadband Internet access is an "information service," not a "telecommunications service." Under federal law, a "telecommunications service" is subject to local and federal regulations, including a requirement that one firm let others access its lines. "Information services" are not.

The FCC's ruling was overturned by the 9th Circuit after a California Internet service provider called Brand X -- with support from consumer groups and several Pennsylvania townships -- filed a challenge.