US SUPREME COURT DECISIONS

Where a patent is infringed by selling machines embodying improvements covered by the patent and the value of the machines as marketable articles is attributable in part to the patented improvements and in part to unpatented parts or features, the profits arising from the infringing sales belong to the owner of the patent insofar as they are attributable to the patented improvements, and insofar as they are due to the other parts or features, they belong to the seller.

Upon an accounting in a suit for such infringement the commingled profits resulting from selling the machines in completed and operative form should be separated or apportioned between what was covered by the patent and what was not covered by it.

If the plaintiff's patent covered only a part of the infringing machine and created only a part of the profits, he is required to take the initiative in presenting evidence looking to an apportionment.

In an apportionment of profits, mathematical exactness is not indispensable, reasonable approximation being what is required, and it usually may be attained through the testimony of experts and persons informed by observation and experience.

The result to be accomplished by an apportionment is a rational chanrobles.com-red

Page 235 U. S. 642

separation of the net profits so that neither party may have what rightfully belongs to the other.

Where damages are sought for infringing sales and it does not appear that the plaintiff thereby lost the sale of a like number of machines or of any definite or even approximate number, no adequate basis is laid for an assessment of damages upon the ground of lost sales.

As the exclusive right conferred by a patent is property and infringement of it is a tortious taking of a part of that property, the normal measure of damages is the value of what was taken, and this may be shown by proof of an established royalty, if there be such, and, if not, by proof of what would have been a reasonable royalty considering the nature of the invention, its utility and advantages, and the extent of the use involved. Coupe v. Royer, 155 U. S. 565, explained.

The right conferred by a patent under our law is confined to the United States and its territories, and infringement cannot be predicated of acts wholly done in a foreign country.

In the particular circumstances of this case, the decree, although ordinarily requiring affirmance, is reversed in order that there may be an opportunity to produce further evidence upon the accounting and to take other proceedings in conformity with this Court's opinion.

183 F.3d 4 reversed.

The facts, which involve the construction and application of certain provisions of the patent laws of the United States in regard to liability for infringement, are stated in the opinion.