Powers-Kennedy Contracting Corp. v. Concrete Mixing & Conveying Co.
Headline: Court rejects a patent on a concrete-transporting machine as uninventive, reversing one infringement win and upholding another court’s finding of invalidity, freeing competing equipment makers to continue similar work.
Holding:
- Declares the McMichael concrete-transport patent invalid, removing its enforceable monopoly.
- Reverses an infringement ruling and affirms another court’s invalidity decision.
- Allows makers of similar concrete equipment to operate without this patent stopping them.
Summary
Background
An inventor, John H. McMichael, and his company held a 1915 patent for a machine and method to move and treat concrete using a hopper, compressed air above the mass, a lower air pipe, and a U-shaped bend in the delivery duct. Two lower-court battles produced opposing results: one court found the patent valid and infringed, while another federal court held it void for lack of novelty. The Supreme Court agreed to hear both cases together because of that conflict.
Reasoning
The central question was whether McMichael’s patent showed a real new invention or just combined known parts. The Court examined the patent’s features and the prior devices described in the record. It found the hopper shape, use of air behind the material, booster nozzles, and related arrangements already known in earlier patents and practice. The Court also rejected the theory that jets of air cut concrete into piston-like “slugs,” noting the patent’s own description and evidence did not support that operation. Because the claimed device merely combined old elements and similar prior work (including evidence that another inventor’s application predated McMichael’s), the Court concluded there was no patentable invention.
Real world impact
The ruling invalidates the McMichael patent, so the Court did not need to decide detailed infringement issues. One lower court’s judgment finding infringement was reversed, and the other court’s invalidity ruling was affirmed. Manufacturers and users of similar concrete-handling equipment are no longer blocked by this patent from making or using comparable machines.
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