Obviousness in Patents
A patent is granted for new, useful, and non-obvious inventions. Courts tend to define terms for consistency. The traditional test for obviousness has been that there should be a teaching, motivation, or suggestion (TSM) for the invention to be obvious.
In KSR v. Teleflex (2007) the Supreme Court ruled that the traditional test is too rigid and goes against common sense when the invention is obvious for other reasons. One of the reasons can be that there is a market demand for a solution out of a handful of possible solutions.