Of course, all the above is chickenfeed. The best way to steal from your employer is self-plagiarism. This means selling the copyright on your work twice. Say you're a musician, you get hired to write music for 2 TV shows, you use the same work in both. Or you're contracted to write an album. Why bother producing new songs when you can copy some you've already recorded for other record labels under other contracts?

One famous case of this in recent years was the singer John Fogerty, who was sued by Fantasy Inc, who owned the copyright for his song "Run Through the Jungle" for allegedly copying it in his later composition "The Old Man Down the Road". The result was a copyright infringement suit like any other: the same standards were applied as if Fogerty had not written the first song.

This also works for a wide variety of creative professions, indeed any job which involves the creation of intellectual property. Computer programmers can write exactly the same piece of software for multiple companies - it's common to hire people to do work they've already done for another firm, even for rivals (especially for rivals). Some architects seem to produce essentially the same building over and over again for client after client. It is also a popular activity among students, who may try and submit the same essay or artwork more than once to different teachers.

Although this is generally illegal or at least will render you guilty of breach of contract or open to civil lawsuits like Fogerty, or for a student thrown out of college, in fact it is commonplace to a degree. If a famous recording artist moves from Atlantic to Dreamworks, does the new company expect them to produce wholly new work, different in style and format? Of course not. It's all a very fine line.

Or, as Alfred Hitchcock put it, "Self-plagiarism is style."