Yet under copyright law, which treats the product of employees and contracted freelancers as the work of the company from the moment of creation, Ditko owns no part of Spider-Man.

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The Supreme Court decided that the VCR was not illegal because the product is capable of important uses that do not infringe on copyright.

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Professor Harnad argues that what is at issue is what he calls 'self piracy': copyright was drafted to protect the author from theft of his product - but academics would be dealing with their own work, so comparisons with the widespread net piracy of music, text or software do not apply.

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And although the court said that firms will not be held responsible if they discover only after launching a product that it is being used for illegitimate ends, there is considerable scope for interpretation over what may constitute encouraging copyright piracy.

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