by John Marshall Harlan

“ I am of opinion that when the government, by its agent, knowingly uses or permits to be used for its benefit a valid patented invention, it is liable to suit in the court of claims for the value of such use, and that its liability arises out of contract based upon the constitutional requirement that private property shall not be taken for public use without just compensation. ”

“ The constitution imposing that obligation is a covenant between the government and every citizen whose property is appropriated by it for public use. If Schillinger's patent was valid, then the government is bound by an obligation of the highest character to compensate him for the use of his invention, and its use by the government cannot be said to arise out of mere tort, at least when its representative did not himself dispute, nor assume to decide, the validity of the patent. ”

“ Campbell, 104 U.S. 357, this court said: 'That the government of the United States, when it grants letters patent for a new invention or discovery in the arts, confers upon the patentee an exclusive property in the patented invention which cannot be appropriated or used by the government itself, without just compensation, any more than it can appropriate or use, without compensation, land which has been patented to a private purchaser, we have no doubt. ”