Henry McKervey and Declan Long, in "Makers and Takers: Art and the Appropriation of Ideas:
[I]t is the expression of an idea which is subject to legal protection. While perhaps this has meant that an artist such as Gillian Wearing can be faced with difficulties over the unattributed re-application of her work, the law also could be said to give artists a relative amount of freedom to take and re-use material in any number of subtly different ways without the spectre of plagiarism remaining ever-present. In a work such as Douglas Gordon's 24 Hour Psycho, for instance, there is in one sense very little of the artist's 'own' work (Hitchcock's classic thriller being merely re-played at a radically slowed-down pace) yet Gordon's intervention makes for a powerful, transformative artistic statement. The question of "knowing originality when you see it" is almost beside the point in cases such as this: artists' strategies of appropriation prompt questions of originality to become thematically intriguing on, one level, while also being critically irrelevant and, on occasion, inappropriate, on another.