The ruling by U.S. District Judge Jeremy Fogel of San Jose was the first in the nation to require the owner of the rights to a creative work to consider whether an online copy was a "fair use" - a small or insignificant replication that couldn't have affected the market for the original - before ordering the Web host to take it down.

A 1998 federal law authorized copyright holders to issue takedown orders whenever they see an unauthorized version of their work on the Internet without having to sue and prove a case of infringement. Some advocates of Internet users' rights - including the Electronic Frontier Foundation, which represented the individual user in this case - contend the procedure has been abused.

The case dates from February 2007, when Stephanie Lenz, a writer and editor from Gallitzin, Pa., made a video of her 13-month-old son cavorting to Prince's song "Let's Go Crazy" and posted the 29-second clip on YouTube.

Four months later, Universal Music Corp., which owns the rights to the song, ordered YouTube to remove the video and nearly 200 others involving Prince compositions. Lenz, exercising her rights under the same 1998 law, notified YouTube several weeks later that her video was legal and ordered it restored. YouTube complied after waiting two weeks, as required by law, to see whether Universal would sue Lenz for infringement.

Lenz then sued Universal in Northern California, YouTube's home district, for her costs, claiming the music company had acted in bad faith by ordering removal of a video that - she contended - was obviously a fair use of the song and had no commercial value.

Universal denied her claim and argued that the 1998 law doesn't require copyright holders to decide whether a copied work is a fair use before ordering it taken down. Fair use is never obvious, the company argued, and the inquiry would be so cumbersome and time-consuming that it would thwart the purpose of the law authorizing takedowns.

But Fogel noted Wednesday that the law defines a fair-use copy as legal and said the copyright holder, who has to examine the Web posting to make sure it's an unauthorized duplicate, must also consider whether the excerpt was too innocuous to matter commercially.

In most cases, the judge said, that inquiry "will not be so complicated as to jeopardize a copyright owner's ability to respond rapidly to potential infringements." The law is intended "to prevent the abuse of takedown notices," he said.

Fogel, who will next consider whether Universal's takedown order was legal, said he's allowing the case to continue even though he has "considerable doubt" that Lenz can prove the company acted in bad faith.

Universal spokesman Peter Lofrumento told the Associated Press that the company remains "confident that we will prevail in this matter."

E-mail Bob Egelko at begelko@sfchronicle.com.

This article appeared on page A - 2 of the San Francisco Chronicle