Duffy presided over the copyright case Grand Upright Music, Ltd. v. Warner Bros. Records Inc. 780 F. Supp. 182 (S.D.N.Y. 1991), in which Warner was sued over the use of the sampling of Raymond "Gilbert" O'Sullivan's "Alone Again (Naturally)" by rapper Biz Markie in his song "Alone Again". Duffy has been criticized for his opinion in Grand Upright v. Warner, not because the decision was wrong, but because Duffy begins his opinion with the biblical admonition – "thou shalt not steal" and later referred the defendant to the U.S. Attorney suggesting criminal charges. According to The Copyright Infringement Project of UCLA Law and Columbia Law School, Judge Duffy's opinion in Grand Upright v. Warner, "an iffy understanding on the part of this judge of the facts and issues before him in this case."The Copyright Infringement Project: Grand Upright v. Warner
