machine to another without having any interest in or under the patent, he will be estopped from prosecuting his vendee for infringement on the basis of any after acquired title. And where a person sells a patent which employs an invention which infringes a prior patent; the person selling is estopped from bringing an action against his grantee for that infringement; and that estoppel operates as a license not only as against the seller but also as against owners in common with him of the prior patent.'

§ 314. An actual recovery of a full license fee, in an infringement suit for unlicensed making and selling a specimen of a patented thing, operates as an implied license to the purchaser of that specimen, to use it to the same extent that he could lawfully have done, if the infringer had been licensed to make and sell it.' But to effect such a result something more than a judgment or a decree is necessary. There must be a satisfaction of that decree or judgment. And where the money recovered in an infringement suit for unlicensed making and selling a specimen of a patented thing, is recovered as damages for such making and selling alone, that recovery does not operate as an implied license authorizing the use of that specimen.* Recoveries based on unlicensed use of a patented process or thing, are necessarily confined to such use as occurred before the suit was brought, if the action be at law, or to such as occurred before the final decree, if the action is in equity; and it therefore follows that no such recovery can operate to license any one to continue such use, or to begin a new use of that thing or that process."

1 Curran v. Burdsall, 20 Fed. Rep. 835, 1883.

Spaulding . Page. 1 Sawyer, 709, 1871; Perrigo v. Spaulding, 13 Blatch. 391, 1876; Steam Stone Cutter Co. v. Mfg. Co. 17 Blatch. 31, 1879; Booth v. Seevers, 19 Off. Gaz. 1140, 1881; Stutz v. Armstrong, 25 Fed. Rep. 147, 1885.

3 Gilbert & Barker Mfg. Co. v.

Bussing, 12 Blatch. 426, 1885; Fisher v. Amador Mine, 25 Fed. Rep. 201, 1885; Tuttle v. Matthews, 28 Fed. Red. 98, 1886; American Bell Telephone Co. v. Albright, 32 Fed. Rep. 287, 1887.

4 Birdsell v. Shaliol, 112 U. S. 485, 1884.

Suffolk Co. v. Hayden, 3 Walelac, 315, 1865.

CHAPTER XIII.

INTERFERING PATENTS.

315. Causes and characteristics of interfering patents.

316. Actions in equity between interfering patents.

317. The proper issues in such actions.

318. The force of the decision of

the Commissioner of Patents on a prior interference in the Patent-Office.

319. Injunctions in interference actions.

320. The proper decrees in such actions.

§ 315. PATENTS which contain one or more claims in common, are interfering patents. All but one of several such patents are necessarily void, as to the interfering claim or claims; though all may be valid as to the other claims. which they respectively contain.' There are two causes which lead to the granting of interfering claims. Such claims may be granted because of inadvertence or erroneous judgment on the part of the Patent Office; and they may be granted because applications do not always happen to be made in the order of invention. The first cause may operate when the Patent Office examiners overlook an anticipating patent, while examining an application in point of novelty; or when they form an erroneous opinion that an existing patented claim is substantially different from the claim under immediate inspection. The second cause may operate when one person who is an original, but not the first, inventor of a particular thing, applies for and receives a patent thereon, before another person, who is an original and the first inventor of that thing, files his application in the Patent Office. Under such circumstances, it is the duty of the Commissioner to declare an interference between the patent and the unpatented application, and if,

1 Gold and Silver Ore Co. v. Disintegrating Ore Co. 6 Blatch. 311, 1869.

in that interference proceeding, the latter applicant is adjudged to be the prior inventor, and if the application is otherwise unobjectionable, it becomes the duty of the Commissioner to grant him a patent.' The Commissioner has however no authority to recall the patent theretofore granted to the wrong party. That patent can be set aside by the courts alone.

§ 316. A suit in equity is the prescribed proceeding by means of which the interfering claims of two or more patents may be adjudicated upon, in point of comparative novelty. Such an action may be joined with an action for infringement. The complainant in such a suit may be the patentee or assignee of either of the interfering patents, or a grantee or licensee thereunder; for all of these persons fall within the category mentioned in the statute: a category which includes every person interested in any one of the patents, or in the working of the invention claimed under any of them. The defendant may be any patentee, assignee or grantee who owns an interest in another of the interfering patents; for all such persons are "owners" thereof. It is neither necessary that all the possible complainants should join in a suit, nor that all the possible defendants should be brought before the court. The statute provides that no decree entered in such a suit shall affect either patent, except so far as the patent affected is owned by parties to the suit, or by persons deriving title under them after the rendition of such decree. The proper practice is to make all persons complainants who have a right, and who are willing, to be so made; and to make all persons defendants who are liable to be made so, and who reside in the district where the suit is brought. No person who does not reside in that district can be made a party

Revised Statutes, Section 4904; Hubel v. Dick, 28 Fed. Rep. 139, 1886.

2 Revised Statutes, Section 4918.

3 Leach v. Chandler, 18 Fed. Rep. 262, 1883; Swift . Jenks, 29 Fed. Rep. 642, 1887; Holliday . Pickhardt, 29 Fed. Rep. 853, 1887.

defendant to a suit of this kind, any more than to any other equity suit in a Federal court.'

A bill cannot be filed in an interference suit, until the complainant's patent is actually granted;' and until the defendant's patent is actually granted, there is no occasion for such a bill. No cross-bill is either necessary or proper in a suit of this kind, because the statute provides that in such a suit, the court may adjudge either of the patents to be void. The defendant may therefore obtain all rightful affirmative relief without becoming himself a complainant in a cross-bill.'

§ 317. There may be an issue of law in an interference suit depending upon the construction of the various letters patent involved therein, and consisting of the question of the presence or absence of interference between them; and such an issue when it arises in such a suit may be decided on a demurrer. There is but one issue of fact in an interference suit. That issue relates to the dates wherein the interfering matter was respectively invented by the interfering inventors. If the complainant's invention is the older, the defendant's interfering claim is void for want of novelty. And the complainant's interfering claim is void for want of novelty, if the defendant's invention is found to antedate the other. Evidence that a third person anticipated both inventors, is not admissible in an interference suit; because such evidence is not relevant to any decree the court has jurisdiction to make in such a case. Such evidence, if acted upon, would result in a decree voiding both patents. The statute authorizes a decree voiding either patent, but authorizes none voiding both. A decree voiding one, is not a decree impliedly validating the other. Such a decree leaves the successful patent open to every possible objection save want of novelty; and leaves it open to every possible objec

124 Statutes at Large, Ch. 373, p. 552; Liggett & Myers Tobacco Co. v. Miller, 1 McCrary, 31, 1880.

2 Hoeltge v. Hoeller, 2 Bond, 388,

3 Lockwood v. Cleveland, 6 Fed. Rep. 721, 1884.

4 Morris v. Mfg. Co. 20 Fed. Rep. 121, 1884.

tion of want of novelty, save such as might otherwise have been based on the existence of the unsuccessful patent; and leaves it open also to that objection, as between all persons, except the parties to the interference suit and their privies. If a defendant in an interference suit may attack the complainant's patent on the ground that a third person anticipated the complainant's invention, he may, with equal propriety attack it on any or all of the numerous other grounds upon which patents may be attacked in point of validity. To suppose that the statute of interference suits authorizes any such extended litigation, is apparently to misapprehend its purpose and misconstrue its language. These views are now sufficiently established,' notwithstanding one district judge has decided the point in the opposite direction."

§ 318. The evidence upon which interference suits are decided, consists of the best evidence on the question in issue. On this question the Commissioner's decision is prima facie evidence in favor of the patent last granted; because he would not have granted it if he had not decided it to be entitled to priority in point of date of invention.' The Commissioner's decision is not conclusive; because, if it were, the court would have no function but to enforce that decision; and because, if it were conclusive in law, it would bind nobody but the senior patentee. In such a case the operation of a decree based on a Commissioner's decision, if wrong in fact, would be to deprive a patentee of all right to make, use or sell the thing which he was the first to invent and the first to patent; and to throw that invention open to the residue of the world.*

The law of evidence, if applicable to depositions taken in a Patent Office interference, would make those depositions

1

Pentlarge v. Pentlarge, 19 Fed. Rep. 817, 1884; Lockwood v. Cleveland, 20 Fed. Rep. 164, 1884; American Clay Bird Co. v. Clay Pigeon Co. 31 Fed. Rep. 467, 1887.

Foster v. Lindsay, 3 Dillon, 126,

3 Wire Book Sewing Machine Co. v. Stevenson, 11 Fed. Rep. 155, 1882; Chicopee Folding Box Co. v. Rogers,. 32 Fed. Rep. 695, 1887.

Union Paper Bag Machine Co. v. Crane, 1 Holmes, 429, 1874.