Let us suppose, to be supposing, that an enterprising pornographer decides to seek a new market for his dirty pictures. He surmises, correctly, that law students have minds as dirty as the minds of, say, journalism students. So he puts together a law review filled with photographs of nekkid ladies.

Nothing novel here, you say? Ah, but in some of these dirty pictures, the body may be the body of Rosie l'Amour, the famed ecdysiast, but the face is the face of Supreme Court Justice Ruth Bader Ginsburg. The prospect boggles the mind.

As a commercial venture, such an enterprise seems unlikely, but it provides a hypothetical example for Debra Laws in her case against Sony Music Entertainment Inc. The facts are not seriously in dispute.

Debra Laws is a professional vocalist and recording artist. In 1979 she entered into a recording agreement with Elektra Records. Two years later, Elektra released a recording of her song, "Very Special." The ballad must have been at least a modest success, for 20 years later at least some people were still humming or whistling the tune.

In November 2002, an offer came to Elektra: Sony Music wanted permission to use a small "sample" of Laws' "Very Special" in an album it was about to record. The sample amounted to a 10-second segment at the beginning of the album and shorter snippets here and there. Elektra agreed. The album would carry an inconspicuous credit line acknowledging the words of Debra Laws, but there would be no share in royalties and no cash on the line.

Thus was born "All I Have," performed by recording artists Jennifer Lopez and LL Cool J. It turned into a huge commercial success. At one point in 2003 it was the No. 1 song in the United States. The recording has netted the producers more than $40 million.

So much money! And all Laws got was this lousy credit line? In February 2003, she sued Sony in California's state courts, charging the producer with misappropriation of her name and voice. The action soon shifted to U.S. District Court, where Sony moved successfully for summary judgment. A panel of the 9th U.S. Circuit unanimously affirmed. Now Laws seeks Supreme Court review.

For most lawyers, readers and newspaper reporters, copyright law is unknown territory. This case arises under the Copyright Clause in the Constitution's Article I, Section 8. It protects authors and inventors from infringement of their "writings and discoveries," and by extension, infringement of a singer's songs. From this grant of power has grown the forest of statutory law now embedded in Title 17 of the U.S. Code. That is where Ms. Lopez's "All I Have" has landed.

Back to the 9th Circuit: Writing for the panel, Judge Jay S. Bybee ruled for Sony all the way. Judges Jerome Farris and Ferdinand F. Fernandez concurred. A decisive precedent, the panel agreed, may be found in a suit brought by Nancy Sinatra 40 years ago against Goodyear Tire & Rubber Co. Brought under state law, the suit involved Goodyear's use of a song that she had made famous, "These Boots Are Made for Walkin'." The court ruled that the Copyright Act pre-empted her claim.

The 9th Circuit reconfirmed its Sinatra opinion in 1988 in another case involving a familiar figure in the entertainment world, Bette Midler. She brought suit when a professional imitator made a recording of "Do You Want to Dance?" The court ruled again that "a voice is not copyrightable." Sounds are not "fixed" in a tangible medium of expression. Midler was seeking relief from an unauthorized vocal imitation used for advertising automobiles. No way!

Again in 1992, in Tom Waits v. Frito-Lay , the 9th Circuit stuck to its view that singers cannot rely upon copyright law to protect them against imitations of their voices. But in the case at hand, Jennifer Lopez was not imitating Debra Laws' rendition; she was using the original recording with the permission of Laws' agent. Elektra had done what agents do. If Laws was unhappy with her crust of credit, she could sue Elektra under contract law instead of suing Sony in tort.

In its petition to the Supreme Court, Laws' counsel argues that if Judge Bybee's opinion is affirmed, the likeness of any prominent person could be used without his consent on any licensed work that is subject to copyright. On that theory, would Justice Ginsburg have an action against the publisher of Lust magazine? We'll see.