SAMPLES MUST BE LICENSED
Is sampling theft? When rapper Biz Markie sampled the melody of Gilbert O'Sullivan's 1972 hit "Alone Again, (Naturally)" for his song "Alone Again" on his 1991 album I Need a Haircut, he was only following in the footsteps of countless other rappers. Unlike the others, however, Markie went to court. After O'Sullivan denied Markie the right to use his song, Markie used the sample anyway, and O'Sullivan filed suit. Ignoring the nuances of copyright law and artistic creation, Judge Kevin Thomas Duffy likened Biz Markie to a common thief, stating, "Thou shalt not steal has been an admonition followed since the dawn of civilization." Upon rendering his verdict, which included an injunction against the future distribution of the album and the song, Judge Duffy referred the case to a U.S. district attorney for possible criminal prosecution. Although Biz never served time for his alleged violation of the Seventh Commandment, the case did set the precedent for viewing unlicensed sampling as a crime.
http://www.illegal-art.org/audio/historic.html