The D.J. Girl Talk has won positive reviews for his new album and news media attention for its Radiohead-style pay-what-you-want pricing, and on Friday night he is scheduled to play a high-profile gig at the All Points West festival in Jersey City. Not bad for an artist whose music may be illegal.

Girl Talk, whose real name is Gregg Gillis, makes danceable musical collages out of short clips from other people’s songs; there are more than 300 samples on “Feed the Animals,” the album he released online at illegalart.net in June. He doesn’t get the permission of the composers to use these samples, as United States copyright law mostly requires, because he maintains that the brief snippets he works with are covered by copyright law’s “fair use” principle (and perhaps because doing so would be prohibitively expensive).

Girl Talk’s rising profile has put him at the forefront of a group of musicians who are challenging the traditional restrictions of copyright law along with the usual role of samples in pop music. Although artists like the Belgian duo 2 Many DJs have been making “mash-ups” out of existing songs for years, Girl Talk is taking this genre to a mainstream audience with raucous performances that often end with his shirt off and much of the audience onstage.

On a sweltering July afternoon Mr. Gillis, 26, who lives in Pittsburgh, opened his laptop on the bar at the Knitting Factory in TriBeCa and discussed how he builds songs out of samples. Clad in a black T-shirt, jeans and a blue sweatband to tame his long hair, he looked less like a club D.J. than a member of a rock band. Mr. Gillis, who said he saw “Feed the Animals” as an album of his own work rather than a D.J. mix, spent several months testing out ideas during live performances, then several more matching beats and polishing transitions. He estimates that each minute of “Feed the Animals” took him about a day to create.