[1] Although utility can be demonstrated by commercial success, it only requires that the invention is directed to a practical use and that it does what is indicated in the patent.
[2] An invention is useful if it does what it promises; following the directions should result in the desired effect.
This is a question of fact, and there are three prongs to the doctrine:[7] The grant of a patent gives the inventor a monopoly in the market for its product.
The requirement that the invention is useful ensures that society receives accurate and complete disclosure.
By ensuring that these inventions are not speculation or misinformation, the public domain remains uncluttered.