The 6th Circuit Court of Appeals (TN) held digital sampling of a sound recording, no matter how minimal, constitutes copyright infringement. See Bridgeport Music, Inc. et al. v. Dimension Films et al.; Case Nos. 02-6521, 03-5738; September 7, 2004. Read the decision here.
Cf. Newton v. Diamond, Horowitz, and Yauch; 9th Circuit Court of Appeals (CA), 349 F 3rd 591, Nov. 4, 2003. Read the decision here.