By rejecting sweat of the brow doctrine in the context of patents, patent law has become divorced from its underlying economic justification: the prevention of free-riding. The magnitude of the disincentive created by free-riding depends very much on the capital investment that went into the invention.

Odd, I had always understood the underlying justification to be the establishment of free-riding. In return for a temporary monopoly, everyone would be able to use the same superior technique.