[throwawaykf05]

>Patents in all fields clearly slow down innovation by allowing the holder to slow down or stop derivative works.

This theory is not supported by empirical evidence. There is plenty of evidence showing how industries became more innovative with the introduction of patent protection. This theory may however apply to industries where innovation is incremental and where claim boundaries are hard to define, like software, but evidence is hard to come by and only now are we seeing some empirical studies on the matter.