This paper outlines the utilitarian theory and objectives of the U.S. patent system, how the system has been applied to agricultural biotechnology, the “patent thicket” that has resulted, and the general pro-patent orientation of the U.S. Patent and Trademark Office.
Link
http://econpapers.repec.org/scripts/redir.pl?u=http%3A%2F%2Fwww.rff.org%2Fdocuments%2FRFF-DP-02-51.pdf;h=repec:rff:dpaper:dp-02-51