Abandonment of patent

What does Abandonment of patent mean in American Law?

The definition of Abandonment of patent in the law of the United States, as defined by the lexicographer Arthur Leff in his legal dictionary is:

A possible but rarely sustained defense to an infringement of patent suit that the holder of an actually issued patent has abandoned it by acts inconsistent with the holding of a patent, e.g., allowing use of the invention by unlicensed third parties, failing to sue others for infringement, etc. Abandonment of patent is not lightly implied.