35 U.S.C. 101 Inventions patentable
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.C. 101 has been interpreted as imposing four requirements.
First, whoever invents or discovers an eligible invention may obtain only ONE patent therefor. This requirement forms the basis for statutory double patenting rejections when two applications claim the same invention, i.e. claim identical subject matter. See MPEP § 804 for a full discussion of the prohibition against double patenting.
Second, the inventor(s) must be the applicant in an application filed before September 16, 2012, (except as otherwise provided in pre-AIA 37 CFR 1.41(b)) and the inventor or each joint inventor must be identified in an application filed on or after September 16, 2012. See MPEP § 2137.01 for a detailed discussion of inventorship, MPEP § 602.01(c)et seq. for details regarding correction of inventorship, and MPEP § 706.03(a), subsection IV, for rejections under 35 U.S.C. 101 and 115 (and pre-AIA 35 U.S.C. 102(f) for applications subject to pre-AIA 35 U.S.C. 102) for failure to set forth the correct inventorship.
Third, a claimed invention must be eligible for patenting. As explained in MPEP § 2106, there are two criteria for determining subject matter eligibility: (a) first, a claimed invention must fall within one of the four statutory categories of invention, i.e., process, machine, manufacture, or composition of matter; and (b) second, a claimed invention must be directed to patent-eligible subject matter and not a judicial exception (unless the claim as a whole includes additional limitations amounting to significantly more than the exception). See MPEP § 2106 for a detailed discussion of the subject matter eligibility requirements and MPEP § 2105 for special considerations for living subject matter.
Fourth, a claimed invention must be useful or have a utility that is specific, substantial and credible. See MPEP § 2107 for a detailed discussion of the utility requirement.