That’s pretty hard-hitting (PDF) from the St Louis Fed:

The case against patents can be summarized briefly: there is no empirical evidence that they serve to increase innovation and productivity, unless the latter is identified with the number of patents awarded – which, as evidence shows, has no correlation with measured productivity.

Their solution is just as clear:

Both theoretically and empirically, the political economy of government operated patent systems indicates that weak legislation will generally evolve into a strong protection and that the political demand for stronger patent protection comes from old and stagnant industries and firms, not from new and innovative ones. Hence the best solution is to abolish patents entirely through strong constitutional measures and to find other legislative instruments, less open to lobbying and rent-seeking, to foster innovation whenever there is clear evidence that laissez-faire under-supplies it.

The implied bargain in the patent system of faster progress thanks to enlightened and protected sharing of innovations seems to have broken down or never existed in the first place.

It is also the case that modern “disclosure” in patents is negligible – it is essentially impossible to build a functioning device or software program from a modern patent application, a fact which is especially clear since some patented ideas do not – and cannot – work. A case in point is the patent for moving information through the fifth dimension.