Meanwhile, battles over online "file sharing" of music, movies, books, and software have created a crisis in the entertainment industry, alienated many fans, and failed to resolve the question of how much sharing should be allowed or whether all of it should be stringently prosecuted as a violation of copyright law.

The courts have not always been equal to the task of resolving these copyright conflicts. A constitutional challenge to the Sonny Bono law was rejected by the Supreme Court in 2003. The Court's decision ignored the law's adverse effects on culture, and seemed to suggest that Congress, by continually extending the term of copyright, can freeze the public domain indefinitely. But in the process of fighting this well-publicized case, many defenders of the public interest - archivists, libraries, and scholars among them - began to organize and advocate for changes in the copyright system that could help bring valuable if long-forgotten works into the public domain.

There have already been many lawsuits involving the DMCA. In one early case, the federal government criminally prosecuted a company that created a device to decrypt electronic books. Although a judge rejected the company's defense - that its circumvention device had legitimate (indeed, constitutionally protected) uses that would not infringe the copyrights on e-books - a jury eventually acquitted the company. But in another case, online journalists who distributed "DeCSS," a program for decrypting DVDs, were found to have violated the DMCA even though the program could be used in ways that would not infringe copyright. The courts even ordered the defendants to remove links on their Web site to other sites that contained the DeCSS code.

To fight online file-sharing, the music industry went to court to shut down Napster. New, less centralized systems like Grokster and KaZaA, however, quickly replaced Napster, and the industry has not so far persuaded the courts that these digital copying and sharing technologies are themselves "contributory" infringers of copyright. But the war against file-sharing has only intensified. In late 2003, the industry sued more than 200 individuals, including teenagers, for sharing music online.

Public interest groups, scholars, librarians, artists, computer scientists, and others in the growing "copyleft" movement are responding to the copyright crisis with projects that encourage the sharing of information and creative works. Some promote and distribute free software. Others are advocating for a more flexible system that would allow material lacking in current commercial value to enter the public domain sooner.

Conflicts between "strong" copyright control and free expression today thus occupy center stage in the public policy arena. The diversity and vitality of our culture depends on resolving these conflicts in a way that maximizes artistic and intellectual freedom.