| U.S. Circuit Court for the District of Massachusetts | May 15, 1819
Independent of every other objection, there is one, which seems admitted in point of fact, and is certainly established in evidence, that is decisive against the plaintiffs. It appears that the plaintiffs obtained a patent in September, 1810, substantially for the same invention, and improvements, which- are contained in the patent, on which they now sue. That patent remains in full force and unre-pealed. It cannot be, that a patentee can have in use at the same time two valid patents for the same invention; and if he caff successively take out at different times new patents for the same invention, he may perpetuate his exclusive right during a century, whereas the patent act confines this right to fourteen years from the date of the first patent. If this proceeding could obtain countenance, it would completely destroy the whole consideration derived by the public for the grant of the patent, viz. the right to use the invention at the expiration of the term specified in the original grant. I hold it to be the necessary conclusion of law, that the inventor can have but a single valid patent for his invention; and that the first he obtains, while it remains unrepealed, is an estoppel to any future patent for the same invention founded upon the general patent act. The public have by the first patent acquired an inchoate interest, which cannot be defeated by any merely ministerial acts of the officers of the government.
[For another case involving this patent, see Case No. 10,432.]