1. The subject matter is statutory subject matter
2. The invention is useful
3. The invention is novel
4. The invention is nonobvious
5. The patent application meets the written description requirement
6. The patent application meets the enablement requirement
7. The invention meets the best-mode requirement
The first four requirements – statutory subject matter, utility, novelty and nonobviousness – can be checked before drafting the application. The next three requirements – written description, enablement and best-mode – can be checked after the application is drafted.
The utility requirement is set forth in 35 U.S.C. § 101. It is not a stringent requirement. It is usually an issue when an inventor tries to patent a perpetual-motion machine, a composition of matter that has no obvious useful purpose, a general “cure for cancer” or similar invention.