Not all inventions are eligible for patent protection. Eligibility requires that the invention: covers eligible subject-matter, is useful, is novel, is nonobvious, and is adequately disclosed in a patent application. See 35 U.S. Code §101, §102, §103, and §112.
Patent protection is limited to a process, machine, manufacture, or composition of matter.
“Non-limiting examples of claims that are not directed to one of the statutory categories: ... transitory forms of signal transmission[,] a human per se, … a legal contractual agreement between two parties, … a computer program per se, … a company, … a mere arrangement of printed matter, … data per se”.
— Manual of Patent Examining Procedure, Chapter 2100, Section 2106.
Patent protection is limited to useful inventions.
“Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.”
— 35 U.S. Code § 101.
An invention is not eligible for patent protection when the invention is available to the public prior to filing a patent application.
“A person shall be entitled to a patent unless (1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention; or (2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.”
— 35 U.S. Code § 102.
Patent protection is limited to inventions that are not obvious to a person of ordinary skill in the art.
“A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains.”
— 35 U.S. Code § 103.
A patent application must adequately disclose the invention.
“The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same[.]”
— 35 U.S. Code § 112 (a).
These five requirements shape the grant and review of patents at the USPTO. They also shape validity challenges that arise in U.S. district courts and in post-grant proceedings at the USPTO.