Hotchkiss v. Greenwood (1850)

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A patent was issued for clay/porcelain knob featuring a metal shank. "new and useful improvement in making door and other knobs of all kinds of clay used in pottery, and of porcelain" which featured "a cavity in which the screw or shank is inserted by which they are fastened largest at the bottom of its depth, in form of a dovetail, and a screw formed therein by pouring metal in a fused state."

Court Ruling:

This patent was ruled invalid by the court, though one justice formed a dissenting opinion.


As the case syllabus states, "The knob was not new, nor the metallic shank and spindle, nor the dovetail form of the cavity in the knob, nor the means by which the metallic shank was securely fastened therein. Knobs had also been used made of clay. The only thing new was the substitution of a knob made out of clay in that peculiar form for a knob of metal or wood. This might have been a better or cheaper article, but is not the subject of a patent."

The superiority of the knob consisted in the superiority of the substituted material (the clay), which is inherent to the material itself, and cannot be attributed to an inventor.

The dissenting justice, Mr. Justice Woodbury states that he believes that if the knob in question were indeed cheaper and better than those that preceded it, it deserved the protection of a patent. Therein he believes is the true test of patentability, because the reduction in price and the increase in quality/functionality would constitute an improvement worth of a patent.


In essence, the court's ruling with respect to non-obviousness lies in the statement that "unless more ingenuity and skill in applying the old method... were required... 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. In other words, the improvement is the work of a skillful mechanic, not that of the inventor."

The dissenting opinion, which is closest to modern patent law, argued against this claim, and supported an improvement such as a material substitution that made the device better and cheaper as an advancement of science, and as such was a patentable item.