The Supreme Court upheld a 1998 federal law yesterday that extended the life of most copyrights by 20 years, deciding a landmark copyright case in favor of artists, writers and the entertainment industry.

A loose coalition of independent scholars, publishers and Internet archivists had argued that, by lengthening existing copyrights, the law, known as the Sonny Bono Copyright Term Extension Act in honor of the late singer and House member, effectively made those copyrights perpetual -- violating the constitutional provision that says Congress may spur intellectual productivity by granting copyrights for "limited times."

But by a vote of 7 to 2, the court deferred to Congress, holding that it enjoys essentially unfettered power to determine the length of copyrights, as long as it specifies a period. Congress had several reasons to pass the Bono Act, including increasing economic incentives for creative activity, encouraging owners of old movies to restore and distribute them and harmonizing U.S. and European intellectual property law, the court said -- and it is not up to the judiciary to second-guess such policy judgments.

"The [law] reflects judgments of a kind Congress typically makes, judgments we cannot dismiss as outside the Legislature's domain," Justice Ruth Bader Ginsburg wrote in the opinion for the court.

At stake was the future ownership of such icons of Jazz Age American popular culture as early Mickey Mouse cartoons, certain silent films and George Gershwin melodies such as "Rhapsody in Blue," whose copyrights were set to expire early this century -- until Congress approved the Bono Act and President Bill Clinton signed it.

The act extended copyright terms from 50 years after the author's death to 70 years, or, in the case of anonymous or corporate works, 95 years from publication.

In a sense, then, yesterday's case was about the point at which songs, pictures and stories that are widely considered part of the American cultural patrimony will be recognized as such under the law.

Opponents of the Bono Act had also maintained that it should be subject to court review as a possible violation of the First Amendment, since it restricts the free flow of information.

The court swept that argument aside as well.

"[C]opyright's purpose is to promote the creation and publication of free expression," Ginsburg wrote, adding that "copyright law contains built-in First Amendment accommodations" such as the "fair use" doctrine, which permits limited reproduction of copyrighted material by journalists and scholars.

Two justices, Stephen G. Breyer and John Paul Stevens, dissented in separate opinions that argued the Bono Act essentially conferred a windfall on existing copyright holders and their familial or corporate heirs, without any corresponding increase in creative effort or public knowledge.

The case, Eldred v. Ashcroft, No. 01-618, was the first in which the court had been called upon to weigh the constitutionality of a law setting copyright terms; it also confronted the justices with a novel Internet-age political movement, spearheaded by Stanford University law professor Lawrence Lessig, aimed at breaking what its members consider the hammerlock that copyright gives large corporations such as Walt Disney Co. on art and information that should be readily available online.

"[I]f there is any good that might come from my loss," Lessig, who argued the case before the court in October, wrote in a Web posting yesterday, "let it be the anger and passion that now gets to swell against the unchecked power that the Supreme Court has said Congress has."

Lessig noted that his cause enjoyed the support of the Free Software Foundation and such figures as conservative activist Phyllis Schlafly and Nobel Prize-winning economists Milton Friedman and Kenneth J. Arrow.

Jack Valenti, president and CEO of the Motion Picture Association of America, said in a statement that his organization is "pleased that the Court has reaffirmed the absolute authority of Congress to set copyright terms. We have always maintained and the law has long recognized that copyright, whose aim it is to provide incentive for the creation and preservation of creative works, is in the public interest."

The law was strongly backed not only by the heirs of such artistic greats as children's author Theodor Seuss Geisel (Dr. Seuss), but also by Disney, AOL Time Warner and a parade of recording industry stars. Yesterday's majority opinion noted that Congress had decided that extended copyright would give artists more incentives to create, based in part on testimony by Quincy Jones, Bob Dylan and Carlos Santana.

In a statement, Disney pronounced itself "pleased with the court's ruling, which ensures copyright owners the proper incentive to originate creative works for the public to enjoy."

In his dissent, Breyer used economic data to show that the copyright extensions in the Bono Act would grant copyright holders 99.8 percent of the benefits they would get from a perpetual copyright. In contrast, he noted, the costs to researchers of locating and purchasing copyrighted works are prohibitive.

To Breyer, the costs and benefits of the law were so skewed between copyright holders and the public that it "cannot be rationally understood to advance a constitutionally legitimate interest.

"And the qualitative costs to education, learning and research will multiply as our children become ever more dependent . . . upon computer-accessible databases -- thereby condemning that which is not so accessible, say, the cultural content of early 20th-century history, to a kind of intellectual purgatory," Breyer wrote.

But Ginsburg noted that the law included some exemptions for libraries, and that teaching and research would be protected under the "fair use" doctrine. She added that striking down the Bono Act would call into question past copyright extensions as well.

The case began in 1999, after Eric Eldred, who runs an Internet archive called Eldritch Press, discovered that he would have to pay to publish works from the 1920s, such as a collection of Sherwood Anderson stories.

He sued unsuccessfully in U.S. District Court in Washington, and lost again on appeal at the U.S. Court of Appeals for the D.C. Circuit. But the Supreme Court agreed early last year to hear the case.

Disney will keep rights to its Mouse.