Some types of inventions will not qualify for a patent, no matter how interesting or important they are. For example, mathematical formulas, laws of nature, newly discovered substances that occur naturally in the world, and purely theoretical phenomena -- for instance, a scientific principle like superconductivity -- have long been considered unpatentable. In addition, the following categories of inventions don't qualify for patents:
- processes done entirely by human motor coordination, such as choreographed dance routines or a method for meditation
- most protocols and methods used to perform surgery on humans
- printed matter that has no unique physical shape or structure associated with it
- unsafe new drugs
- inventions useful only for illegal purposes, and
- non-operable inventions, including "perpetual motion" machines (which are presumed to be non-operable because to operate they would have to violate certain bedrock scientific principles).