than were possessed by an ordinary mechanic acquainted with the business, there was an absence of that degree of skill and ingenuity which constitute essential elements of every invention.

It was established "that knobs of metal, wood, etc., connected with a shank and spindle, in the mode and by the means used by the patentees in their manufacture, had been before known, and were in public use."

"[9] Therefore, McLean's charge to the jury was correct, "for unless more ingenuity and skill in applying the old method of fastening the shank and the knob were required in the application of it to the clay or porcelain knob than were possessed by an ordinary mechanic acquainted with the business, there was an absence of that degree of skill and ingenuity which constitute essential elements of every invention."

The Court described the invention in these terms: The claim is simply of the combination of the lead and india-rubber in the holder of a drawing-pencil; in other words, the use of an ordinary lead pencil, in one end of which, and for about one-fourth of its length, is inserted a strip of india-rubber, glued to one side of the pencil.

[16]Similarly in 1883 in Atlantic Works v. Brady, the Court used language like that of Hotchkiss in invalidating a patent: "It was never the object of those laws to grant a monopoly for every trifling device, every shadow of a shade of an idea, which would naturally and spontaneously occur to any skilled mechanic or operator in the ordinary progress of manufactures.

"[17] In the 1891 decision in Magowan v. New York Belting & Packing Co., the Court again echoed Hotchkiss – in upholding a patent as valid: "[Wihat Gately did was not merely the work of a skilled mechanic, who applied only his common knowledge and experience, and perceived the reason of the failure of [previous inventions], and supplied what was obviously wanting; and that the present case involves .

While it is entirely true that the fact that this change had not occurred to any mechanic familiar with windmills is evidence of something more than mechanical skill in the person who did discover it, it is probable that no one of these was fully aware of the state of the art and the prior devices, but, as before stated, in determining the question of invention, we must presume the patentee was fully informed of everything which preceded him, whether such were the actual fact or not.

[19]The Court's standard for what was ordinary mechanical skill rose and fell over the years, but began to become more strict after the Great Depression and New Deal.

We cannot conclude that his skill in making this contribution reached the level of inventive genius which the Constitution authorizes Congress to reward. . . .

Strict application of that test is necessary lest in the constant demand for new appliances the heavy hand of tribute be laid on each slight technological advance in an art.

In the A&P case, the claimed invention was a rack or frame with three sides and no top or bottom, which could be used to pull groceries along a counter beside a cash register.

The Court said: The conjunction or concert of known elements must contribute something; only when the whole in some way exceeds the sum of its parts is the accumulation of old devices patentable.

This case is wanting in any unusual or surprising consequences from the unification of the elements here concerned, and there is nothing to indicate that the lower courts scrutinized the claims in the light of this rather severe test.

[25]In a concurring opinion, Justice Douglas collected a list of cases in which the Court had interpreted the Hotchkiss test for invention to require a level of skill embodying "inventive genius": One commentator characterized the 1930–1952 period as "contain[ing] the Supreme Court's most critical attitude towards patents and patent monopolies.

The first Supreme Court decision interpreting the 1952 codification of Hotchkiss was Graham v. John Deere Co.,[27] in which the Court explained that the inherent problem in formulating conditions for patentability "was to develop some means of weeding out those inventions which would not be disclosed or devised but for the inducement of a patent."

"[28] But the Hotchkiss test merely "laid the cornerstone of the judicial evolution" necessary to define the conditions for patentability.

"[30] According to the Graham decision, the major distinction between the language of Hotchkiss and that of § 103 "is that Congress has emphasized 'nonobviousness' as the operative test of the section, rather than the less definite 'invention' language of Hotchkiss that Congress thought had led to 'a large variety' of expressions in decisions and writings."

It also seems apparent that Congress intended by the last sentence of § 103 to abolish the test it believed this Court announced in the controversial phrase "flash of creative genius," used in Cuno Engineering Corp. v. Automatic Devices Corp.[32]But it would be erroneous, the Court further explained, to accept the contentions "by some of the parties and by several of the amici that the first sentence of §  103 was intended to sweep away judicial precedents and to lower the level of patentability."

Rather: We believe that this legislative history, as well as other sources, show that the revision was not intended by Congress to change the general level of patentable invention.

[33]The Court concluded its explanation of the meaning of § 103 with this instruction: [I]t bears repeating that we find no change in the general strictness with which the overall test is to be applied.

The Court concluded: [W]hile the combination of old elements performed a useful function, it added nothing to the nature and quality of the radiant-heat burner already patented.

In KSR International Co. v. Teleflex Inc.,[41] the Court rejected the Federal Circuit's approach to determining obviousness as insufficiently faithful to the Hotchkiss standard as explained in Graham v. Deere.

It concluded by explaining that adherence to the Hotchkiss test is essential: "Were it otherwise patents might stifle, rather than promote, the progress of useful arts."

And it admonished that the Federal Circuit had "analyzed the issue in a narrow, rigid manner inconsistent with § 103 and our precedents.