U.S. Supreme Court
Birdsall v. Coolidge, 93 U.S. 64 (1876)
Birdsall v. Coolidge
93 U.S. 64
1. In an action at law for the infringement of letters patent, the rule as to the measure of damages is that the verdict of the jury must be for the actual damages sustained by the plaintiff, subject to the right of the court to enter judgment thereon for any sum above the verdict not exceeding three times that amount, together with costs.
2. Where the unlawful acts consist in making and selling a patented improvement or in its extensive and protracted use without palliation or excuse, evidence of an established royalty will, in an action at law, undoubtedly furnish the true measure of damages; but where the use is a limited one, and for a brief period, the arbitrary and unqualified application of that rule is erroneous.