I was researching versioning filesystems and came across Tux2, which eventually led me to a discussion on LKML with this tidbit:

Lawyers built the patent system. Tim O'Rielly once asked a patent lawyer how he would feel if other lawyers could patent legal arguments and charge him money to use those arguments in court. Though he tried to twist out of answering that one, eventually he had to admit that he had no answer. This lawyer IIRC is the director of the U.S. Trade and Patent office.

—Daniel Phillips

I think that legal arguments are not too different from any other "business process" (i.e. Amazon's infamous "one-click checkout"), so this argument has a lot of validity.

EDIT: I managed to find a link to the discussion referenced. The lawyer (Patent Office Director Q. Todd Dickinson) wasn't nearly as befuddled as Daniel seems to recall, although he didn't really address the question adequately (or more importantly, the potential problems such a system would allow).