A federal court in New York thought so back in the 70's, and awarded damages against Harrison for copyright infringement for Harrison's famous tune "My Sweet Lord." According to the legal controversy, when he wrong that song Harrison plagiarized Ronnie Mack's song "He's so Fine," made popular in the 1960's by The Chiffons.
This may have been the most famous copyright infringement case in the history of music. Listen to each tune, and share your opinion:
FYI - here is a Wikipedia article about "My Sweet Lord" that mentions the legal controversy and the finding made against Harrison: http://en.wikipedia.org/wiki/My_Sweet_Lord
For the record, I do not think Harrison was guilty, despite the New York court's finding. But hey, I'm a huge Harrison fan so I can't say I'm unbiased.