Gottschalk v. Benson, 409 U.S. 63 (1972), was a United States Supreme Court case in which the Court ruled that a process claim directed to a numerical algorithm, as such, was not patentable because "the patent would wholly pre-empt the mathematical formula and in practical effect would be a patent on the algorithm itself." That would be tantamount to allowing a patent on an abstract idea, contrary to precedent dating back to the middle of the 19th century. The ruling stated "Direct attempts to patent programs have been rejected [and] indirect attempts to obtain patents and avoid the rejection ... have confused the issue further and should not be permitted." The case was argued on October 16, 1972, and was decided November 20, 1972. Prior history The case revolves around a patent application filed by inventors Gary Benson and Arthur Tabbot, for a method for converting binary-coded decimal (BCD) numerals into pure binary numerals on a general-purpose digital computer. The patent examiner at the United States Patent Office, now called the U.S. Patent and Trademark Office or PTO, rejected the patent application as being directed to a mathematical expression. Pure mathematical expressions had been held to be unpatentable under earlier patent laws in Mackay Co. v. Radio Corp. The applicant appealed to the Board of Patent Appeals and Interferences, which affirmed the examiner's rejection. The applicant further appealed to the Court of Customs and Patent Appeals. The Court reversed the Board. Finally, Commissioner of Patents Robert Gottschalk filed a petition for a writ of certiorari to the Supreme Court. The case The law which is applicable to this case is section 101 of the Patent Act of 1952. The question was whether or not the claimed invention was a "process" under the law. The Court held that because the claim was not limited to any particular type of programmable digital computer and neither involved special purpose implementing machinery nor a transformation of substances, as in all prior cases holding processes patentable, the claim would effectively preclude use of the method for any currently known or future invention in any field. Thus the claim was directed to an algorithm alone and therefore was not patentable. In its brief to the Supreme Court, the government asked the Court to hold that no process could be patented unless it claimed either a transformation of substances or was implemented with a newly devised machine.