Robert Cooper Grier

“ Where an inventor finds it profitable to exercise his monopoly by selling licenses to make or use his improvement, he has himself fixed the average of his actual damage, when his invention has been used without his license. If he claims any thing above that amount, he is bound to substantiate his claim by clear and distinct evidence. When he has himself established the market value of his improvement, as separate and distinct from the other machinery with which it is connected, he can have no claim in justice or equity to make the profits of the whole machine the measure of his demand. ”

“ On the contrary, according to my view of the law regulating the measure of damages in cases of this kind, the rule which is to govern is the same whether the patent covers an entire machine or an improvement on a machine. Those who choose to use the old machine have a right to use it without incurring any responsibility; but if they engraft on it the improvement secured to the patentee, and use the machine with that improvement, they have deprived the patentee of the fruits of his invention, the same as if he had invented the entire machine ”

“ It is only where, from the peculiar circumstances of the case, no other rule can be found, that the defendant's profits become the criterion of the plaintiff's loss. Actual damages must be actually proved, and cannot be assumed as a legal inference from any facts which amount not to actual proof of the fact. What a patentee 'would have made, if the infringer had not interfered with his rights,' is a question of fact and not 'a judgment of law.' The question is not what speculatively he may have lost, but what actually he did lose. ”