
-- his first criterion in judging the inventions was that they had to be useful
-- a patent wouldn't be granted to someone who had just come up with another application of something that was already invented (which is one of the reasons he did not apply for any patents himself since most of his so-called inventions he considered adaptations of inventions already in existence)
-- a patent wouldn't given when it was just an old invention built with a different material
-- He was angered by the considerable number of "frivolous" patents that the office received petitions for, stating that their "abuse...is likely to cause more inconvenience than is countervailed by those really useful" (Bedini) and he made provisions to counteract these such as his rule that no patent would be granted for an "invention" that was simply the combination of existing inventions
-- less than half of those who petitioned for patents received them in the end due to the strict rules laid down by Jefferson