Dable Grain Shovel Company v. Flint/Opinion of the Court
The fourth plea is based upon section 7 of the act of March 3, 1839, c. 88, (in force when the patents were granted,) providing that 'every person or corporation who has or shall have purchased or constructed any newly-invented machine, manufacture, or composition of matter, prior to the application by the inventor and discoverer for a patent, shall be held to possess the right to use, and vend to others to be used, the specific machine, manufacture, or composition of matter so made or purchased without liability therefor to the inventor or any other person interested in such invention.' 5 St. 354. In the later statutes, this provision has been re-enacted with the qualification that the machine, manufacture, or composition of matter must have been purchased from the inventor, or constructed with his knowledge and consent. Act July 8, 1870, c. 230, § 37, (16 St. 203; Rev. St. § 4899.)

It is agreed that the machines in question were constructed and put in use in the defendants' grain elevators by the inventor himself, and with his knowledge and consent, while he was in their employment as superintendent of machinery, and before his application for either patent. According to the express terms of the statute, therefore, the defendants had the right to continue to use these specific machines without paying any compensation to him or his assigns, whether asked for or not.

To the argument of the plaintiff's counsel that the statute is unconstitutional as depriving the inventor of his property without compensation, there is a twofold answer,-the patentee has no exclusive right of property in his invention, except under and by virtue of the statutes securing it to him, and according to the regulations and restrictions of those statutes, (Gayler v. Wilder, 10 How. 477, 493; Brown v. Duchesne, 19 How. 183, 195; Marsh v. Nichols, 128 U.S. 605, 612, 9 Sup. Ct. Rep. 168;) and these machines have been set free from his monopoly by his own act, consent, and permission, (Wade v. Metcalf, 129 U.S. 202, 9 Sup. Ct. Rep. 271.) Judgment affirmed. 

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