Hotchkiss v. Greenwood (JWB)

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The Case

  • 1841 – a patent was granted to Hotchkiss (and Davenport and Quincy) for a "new and useful improvement in making door and other knobs of all kinds of clay used in pottery, and of porcelain" by “having the 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 in metal in a fused state”
  • 1845 – Circuit Court of Ohio – Hotchkiss et al. (plaintiffs) sued Greenwood (defendants) over patent rights, but defendants claimed that clay/porcelain knobs were made and sold in New York, New Jersey, Pennsylvania, England, and Germany long before the patent was obtained (as early as 1831 in NY)
    • Defendants claimed the mode of fastening the shank to the knob, as claimed by the plaintiffs, had been known and used before, and had been used and applied to the fastening of the shanks to metallic knobs
    • Plaintiffs claimed that, although the shank/spindle attaching had been used, and a clay/porcelain knob had been used, they had never been used together, and therefore the patent was valid and defendants infringed


  • The only thing new was the substitution of a knob made out of clay instead of metal or wood. This might have been a better or cheaper article, but is not the subject of a patent. It might have had novelty had the knob been made out of a new composition
    • “the knob is 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 is securely fastened therein”
    • “It may afford evidence of judgment and skill in the selection and adaptation of the materials in the manufacture of the instrument for the purposes intended, but nothing more”
  • No more ingenuity and skill was necessary to construct the new knob than was possessed by an ordinary mechanic acquainted with the business, and the patent was void

Similar Case

  • A button with a wood foundation was improved to include a tin face covering, but it was discovered that pre-Revolution buttons had a bone foundation with a tin face covering
  • A new, even better, material does not constitute a patent


  • "if the said knob of clay or porcelain so attached were an article better and cheaper than the knob theretofore manufactured of metal or other materials, the patent was valid."
  • Justice Woodbury: “the direction virtually was to consider it not so, if an ordinary mechanic could have made or devised it; whereas in my view the true test of its being patentable was, if the invention was new, and better and cheaper than what preceded it. “
  • Some discoveries happen by accident, but are still new and useful, and should therefore be allowed patents because they help the community
  • Applying an old machine to a new purpose (‘double use’) does not permit a patent, but in this case “they are not mere double uses of a previous machine or composition, but a double or additional form or composition of an article for a new purpose”