US Patent Statute:
Title 35 of the United States Code

The text to the page herein titled 'US Patent Practice' makes reference to §§ (sections) 101, 102, 103 & 112: patentable subject matter, novelty, obviousness, and written specification, respectively; citing each section as a grounds for rejection during examination.

Each is a section of Title 35 of the United States Code (35 U.S.C.) found in its entirety
by opening the portable document file (pdf) link at the bottom of this otherwise short page.

35 U.S.C. is shorter, and easier to read, than Title 37 of the Code of Federal Regulations (37 C.F.R.) which is often referred to as the 'Patent Rules' which in turn is much shorter if not easier to read than the Manual for Patent Examination Practice (MPEP).

Most pertinently with regard to all these authorities 35 U.S.C. is governing of 37 C.F.R. which is governing of the MPEP along with decisions by the U.S Court of Appeals for the Federal Circuit (CAFC): the top U.S. Patent Court.

Title 35 is the governing statute for patent law in the U.S., in brief, and all CAFC decisions comprise interpretation, essentially, of this statute.