(45 S.Ct.) 170-State of art may be shown to narrow construction of claims in action against assignor of invention by assignee to which patent was issued. V. Chicago & Northwestern Railway Co., 43 5. Patents uses made and to be made of the lands ac- (266 U. S. 342) In 'suit against assignor of invention by assignee to which patent was issued, under Rev. St. § 4895 (Comp. St. § 9439), the state of art may be shown to narrow or qualify the construction of the claims, and to relieve assignor from charge of infringement. 6. Patents 202 (2)-Assignor of invention held not estopped to deny infringement of patent granted assignee, in view of prior art. Assignee of process for making composite No. 1,284,432, held entitled as against assignor electric insulation materials, covered by patent to claim application of process to nonplaniform articles covered by claims 11 and 12, but not to claim method of manufacture of such insulating material, without two-step process of pressure and heat, cooling and baking; estoppel being limited to two-step process, in view of prior art. Certiorari to the United States Circuit Court of Appeals of the Sixth Circuit. Suit by the Westinghouse Electric & Manufacturing Company against the Formica Insulation Company. Judgment of dismissal was affirmed by the Circuit Court of Appeals (288 F. 330), and plaintiff brings certiorari. Affirmed. This is a writ of certiorari to the Circuit Court of Appeals for the Sixth Circuit in a patent suit. The Westinghouse Electric Com*343 pany sued the Formica Com*pany charging it with infringement of claims 11 and 12 of patent No. 1,284,432, issued November 12, WESTINGHOUSE ELECTRIC & MFG. CO. 1918, to the complainant as assignee, on an v. FORMICA INSULATION CO. (Argued Oct. 22, 23, 1924. Decided Dec. 8, 1924.) 1. Patents No. 102. 112(1)—Presumed to be valid. A patent is presumed to be valid, but such presumption is not conclusive. 2. Patents 198-Seal not essential to assignment of patent. Assignment of patent under Rev. St. § 4898 (Comp. St. § 9439), does not require a seal. 3. Patents 129-Assignor estopped to deny validity as against assignee. Assignor of patent is estopped to deny its validity as against assignee. 4. Patents 170-State of art may be shown to narrow or qualify construction of claims in assignee's suit against assignor. In a suit by the assignee of a patent against the assignor for infringement, state of art can be shown to narrow or qualify the construction of the claims, and relieve the assignor from the charge of infringement, but not to destroy the patent, because assignor is estopped to deny its validity. application of O'Conor filed February 1, 1913. The patent covered a process for making composite electric insulation materials using paper, muslin, or other fibrous material. The fabric was to be coated on one side with an adhesive liquid, such as bakelite, a condensation product of phenol and formaldehyde. It was then dried by passing it over a series of rollers in a steam-heated oven. The thickness of the coating retained by the paper was regulated by varying the distance between the two rollers and by altering the viscosity of the liquid. The prepared paper was cut built up to the required thickness by placing into sheets of any desired size, and a plate of each sheet next to the treated side of the the sheets together with the untreated side adjacent sheet. The built-up plate was then placed between thin sheet steel plates on which had been rubbed a small amount of machine oil. Any desired number of the steel plates carrying the sheets of paper were placed between the platens of a hydraulic press which had been previously heated by steam. The press was closed and pressure applied to as much as 800 pounds per square inch. Steam heat was first applied and then For other cases see same topic and KEY-NUMBER in all Key-Numbered Digests and Indexes a cooling period followed. The period of ant's manufacture of its composition and its pressure and heat was varied in proportion large investment in the business without obto the thickness of the plate according to a jection for four years before the claims Nos. table set forth. The effect was firmly to 11 and 12 were secured by the defendant as cement together the sheets of paper and fur-assignee from the Patent Office and did not ther to impregnate the paper with the bake- sue for three years thereafter. lite. Thus the plate was transformed into a hard and compact mass. After cooling, the plates of insulation were removed from the press and clamped between steel plates to prevent warping during the baking. The plates were then placed in ovens, with an air pressure of 140 pounds per square inch, and the temperature regulated between 100 and 140 degrees centigrade. These conditions *344 were maintained for approximately eight hours, when the plates were removed from the oven and the finished product allowed to cool. The specifications further said that while the process was used for plates, the material could be similarly produced in the form of channel pieces or tubes that were cylindrical or rectangular in cross section or of other shape, as desired, by pressing in forms of the proper shape. The resultant material had a specific gravity of approximately 1.25, was practically nonabsorbent, even when soaked in hot water, and was in soluble. The first 10 claims subsequently allowed in the patent referred to the so-called "twostep" process, namely, first, the application of heat and pressure to the superposed sheets and cooling them; and, second the baking of them under a lower pressure. The eleventh and twelfth claims, however, were as follows: In reply the plaintiff urged that the defendant being in privity with O'Conor in the assignment and the infringement was estopped to dispute the validity of the eleventh and twelfth claims construed according to the ordinary meaning of their language, which, as it contended, did not require the two-step process. The District Court sustained the defense based on complainant's laches and dismissed the bill. On appeal, the Circuit Court of Appeals held that the defense of laches could not be sustained. Coming to consider the defense of estoppel, the court held that on the facts no estoppel arose as to the claims sued on, and proceeding then to the merits found that claims 11 and 12 were invalid for lack of invention. O'Conor was a mechanical engineer, and after graduation from college entered the employ of the Westinghouse Company at a small salary, with the understanding that he was to be allowed to work in association with ex perienced engineers and gain experience in the line of his profession, and that inventions made by him when in the company's employ were to become the property of the company and to be assigned by him to it. O'Conor made this invention and disclosed it by written description to the company, which through its legal department prepared his application for a patent and an assignment, both of which he executed, receiving the nominal consideration of one dollar. Thereafter, *346 "11. The process of manufacturing a nonplaniform article which consists in superposing a plurality of layers of fibrous material associated with an adhesive substance that is adapted to harden under the influence of heat and pending the appli*cation for the patent, O'Conpressure into a substantially infusible and in- or left the company's employ and associated soluble condition, and molding the superposed himself in business with two others in the layers by means of a form of the proper shape manufacture of electric insulating material while applying pressure and heat to compact in a partnership, which was thereafter organ"12. The process of manufacturing a non-ized into a corporation known as the Formica planiform article which consists in superposing a plurality of layers of fibrous material associated with a phenolic condensation product and molding the superposed layers by means of a form of the proper shape while applying pressure and heat to compact and harden the materials." and harden the materials. Company, and its stock divided between the partners. From 1913 the partnership and succeeding company have been engaged in the manufacture and sale of laminated products having a phenolic condensation binder. They have made nonplaniform articles, as well as flat plates, openly and with the knowledge and acquiescence of the Westinghouse Company from the beginning in 1913 down to the time this suit was brought, July 6, 1920. in suit was filed and was assigned to the comWhen the application for the patent here pany, there were no claims based on a distinction between flat plates and nonplaniform articles. But the specifications signed by O'Conor contained the following: used for making plates, the insulating material "While the process above described is that may be produced in the form of channel pieces or tubes that are cylindrical or rectangular in (45 S.Ct.) cross section, or of other shape as desired, by pressing in forms of proper shape." The art of making insulating material was well advanced when O'Conor entered it. A a patented invention is limited in a suit for infringement by the assignee. We may first usefully consider the rule that should obtain where the assignment is made after the issue of the patent, and then the difference in the rule, if any, where the assignment was made before the granting of the patent. Haefely patent owned by the Westinghouse Company, when O'Conor began his experiments was for a process for making a [1-3] Congress under its power to secure hard material offering resistance to the elec-for limited times to inventors the exclusive tric current out of paper covered with var-right to their discoveries, has enacted laws nish, wound around a mandrel and subjected conferring such an exclusive right by patent to pressure and heat. The art also showed a after an application with specification of the forming press by Haefely for pressure of flat invention and claims therefor and a favorarticles for such a purpose. There was a able decision by the Commissioner of Patprocess patent to Thomson for making inents. The patent of the exclusive right sulating material by applying to paper sheets against the public carries with it a presumpan earthy or mineral substance with bind- tion of its validity. Agawam Woolen Co. v. ing material, piling such sheets together and Jardon, 7 Wall. 583, 19 L. Ed. 177; Blanchard drying and heating the resulting mass. Baek *347 land had *invented much in this art and all before O'Conor. One of his discoveries was that of the "bakelite" which O'Conor suggests using in his process-a combination of phenol and formaldehyde, a viscous fluid resisting the electric current and attaining great hardness under heat and pressure for use as a binder. Another patent of Baekland was for "a composite cardboard consisting of superposed layers of paper or the like combined with intermediate layers of an insoluble, infusible condensation product of phenols and formaldehyde," in which he described his process as follows: v. Putnam, 8 Wall. 420, 19 L. Ed. 433; Miller 349 "I apply to the surface of any of the ordinary grades of paper, or to asbestos paper or the like, a coating of a liquid condensation product of phenols and formaldehyde of such character that it is capable of transformation under the action of heat into an insoluble and infusible body. For this purpose I may use either a liquid condensation product of the character described, or a solution of the same in alcohol or other appropriate. solvent. This layer is permitted to dry somewhat, when a second cordance with the *statute. Its purpose is to sheet of paper is superposed upon the first and furnish written and recorded evidence of title similarly treated, or the several layers may be and to protect the purchaser of the title as recoated and preferably dried before being super-corded for value without notice. It was manposed. The condensation product may be applied to one or both sides of the sheets. The ifestly intended by Congress to surround the desired number of sheets having been assembled, the composite article is compacted by pressure, with or without the aid of heat. Heat is now applied in order to effect the transformation of the condensation product into an insoluble and infusible body." Messrs. John C. Kerr and Drury W. Cooper, both of New York City, for petitioner. Messrs. Dyrenforth, Lee, Chritton & Wiles, of Chicago, Ill. (John H. Lee, of Chicago, Ill., Frederic D. McKenney, of Washington, D. C., and Wm. H. Dyrenforth, of Chicago, Ill., of counsel), for respondent. *348 conveyance of patent property with safeguards resembling those usually attaching to that of land. This court has recognized the analogy between estates in land by estoppel and the right to enjoy a patent right in the use of an article conveyed by one without au thority but who acquires it by subsequent conveyance. Gottfried v. Miller, 104 U. S. 521, 26 L. Ed. 851; Littlefield v. Perry, 21 Wall. 205, 22 L. Ed. 577. There are no cases in this court in which the application of the principle of estoppel as by deed to the conveyance or assignment of patent property has been fully considered. But there are many in the reports of the Cir *Mr. Chief Justice TAFT delivered the cuit and District Court decisions and in those -opinion of the Court. The important question in this case is the operation of the principle of estoppel on the character of defense to which the assignor of of the Circuit Court of Appeals. They began as early as 1880 in Faulks v. Kamp (C. C.) 3 F. 898, and were followed by a myriad. The rule supported by them is that an assignor of a patent right is estopped to attack the utility, novelty or validity of a patented invention which he has assigned or granted as against any one claiming the right under his assignment or grant. As to the rest of the world, the patent may have no efficacy and create no right of monopoly; but the assignor cannot be heard to question the right of his assignee to exclude him from its use. Curran v. Burdsall, 20 F. 835; Ball & Socket Fastener Co. v. Ball Glove Fastening Co., 58 F. 818, 7 C. C. A. 498; Woodward v. Boston Lasting Machinery Co., 60 F. 283, 284, 8 C. C. A. 622; Babcock v. Clarkson, 63 F. 607, 11 C. C. A. 351; Noonan v. Chester Park Athletic Co., 99 F. 90, 91, 39 C. C. A. 426. There are later cases in nearly all the Circuit Courts of Appeal to the same point. In view of the. usual finality of patent decisions in the Circuit Courts of Appeal, this court will not now lightly disturb a rule well settled by 45 years of judicial consideration and conclusion in those courts. *350 signor assigned would be denied to the court *351 in *reaching a just conclusion. Of course, the state of the art cannot be used to destroy the patent and defeat the grant, because the assignor is estopped to do this. But the state of the art may be used to construe and narrow the claims of the patent, conceding their validity. The distinction may be a nice one but seems to be workable. Such evidence might not be permissible in a case in which the assignor made specific representations as to the scope of the claims and their construction, inconsistent with the state of the art, on the faith of which the assignee purchased; but that would be a special instance of estoppel by conduct. We are dealing only with the estoppel of an assignment based on the specifications and claims without special matter in pais. Mr. Justice Lurton, when Circuit Judge, speaking for the Circuit Court of Appeals of the Sixth Circuit, in Noonan v. Chester Park 427, used this language: Athletic Co., 99 F. 90, 91, 39 C. C. A. 426, "It seems to be well settled that the assignor of a patent is estopped from saying his patent is void for want of novelty or utility, or because anticipated by prior inventions. But this estoppel, for manifest reasons, does not prevent him from denying infringement. To determine such an issue, it is admissible to show the state of the art involved, that the court may see what the thing was which was assigned, and thus determine the primary or secondary character of the patent assigned, and the extent to which the doctrine of equivalents may be invoked against an infringer. The court will not assignee, anything more than that the invention assume against an assignor, and in favor of his presented a sufficient degree of utility and novelty to justify the issuance of the patent assigned, and will apply to the patent the same rule of construction, with this limitation, which would be applicable between the patentee and a stranger." *352 *The analogy between estoppel in conveyances of land and estoppel in assignments of a patent right is clear. If one lawfully conveys to another a patented right to exclude the public from the making, using and vending of an invention, fair dealing should prevent him from derogating from the title he has assigned, just as it estops a grantor of a deed of land from impeaching the effect of his solemn act as against his grantee. The grantor purports to convey the right to exclude others, in the one instance, from a defined tract of land, and in the other, from a described and limited field of the useful arts. The difference between the two cases is only the practical one of fixing exactly what is the subject-matter conveyed. A tract of land is easily determined by survey. Not so the scope of a patent right for an invention. [4] As between the owner of a patent and the public, the scope of the right of exclusion granted is to be determined in the light of the state of the art at the time of the invention. Can the state of the art be shown in a suit by the assignee of a patent against the Circuit Court of Appeals, First Circuit, assignor for infringement to narrow or qual- Ball & Socket Fastener Co. v. Ball Glove ify the construction of the claims and relieve Fastening Co., 58 F. 818, 7 C. C. A. 498; Babthe assignor from the charge? The Circuit | cock v. Clarkson, 63 F. 607, 11 C. C. A. 351; Court of Appeals for the Seventh Circuit in Martin & Hill Cash-Carrier Co. v. Martin, Siemens-Halske Electric Co. v. Duncan Elec- 67 F. 786, 787, 14 C. C. A. 642. Since the tric Co., 142 F. 157, 73 C. C. A. 375, seems Noonan Case, the view thus announced has to exclude any consideration of evidence of been approved in the Circuit Court of Apthis kind for such a purpose. The same view peals of the Second Circuit in Plunger Eleis indicated in subsequent decisions of that vator Co. v. Stokes, 212 F. 941, 943, 129 C. court. Chicago Co. v. Pressed Steel Car Co., C. A. 461; of the Third Circuit in Roessing243 F. 883, 887, 156 C. C. A. 395; Foltz Ernst Co. v. Coal & Coke By-Products Co., 219 Smokeless Furnace Co. v. Eureka Smokeless F. 898, 899, 135 C. C. A. 562; Piano Motors Furnace Co., 256 F. 847, 168 C. C. A. 193. Corporation v. Motor Player Corporation (C. We think, however, that the better rule, in | C. A.) 282 F. 435, 437; of the Fourth Cirview of the peculiar character of patent prop-cuit in Leader Plow Co. v. Bridgewater Plow erty, is that the state of the art may be con- Co., 237 F. 376, 377, 150 C. C. A. 390; of the sidered. Otherwise the most satisfactory means of measuring the extent of the grant the government intended and which the as *And he cites the following cases as sustaining this view: Sixth Circuit in Smith v. Ridgely, 103 F. 875, 43 C. C. A. 365; Babcock & Wilcox Co. v. Toledo Boiler Works, 170 F. 81, 85, 95 C. (45 S. Ct.) C. A. 363; United States Frumentum Co. v., gether has proved more or less unsatisfactory Lauhoff, 216 F. 610, 132 C. C. A. 614; Schie- because of various defects such as absorption bel Toy & Novelty Co. v. Clark, 217 F. 760, resist heat and chemical action, and lack of of moisture from the atmosphere, inability to 763, 133 C. C. A. 490; in the Eighth Circuit in physical strength. Insulating material *** Moon Hopkins Co. v. Dalton Co., 236 F. 936, must be free from these defects and in addition 937, 150 C. C. A. 198; and of the Ninth Cir- must possess high dielectric strength." cuit in Leather Grille & Drapery Co. v. Cristopherson, 182 F. 817, 105 C. C. A. 249. $353 *354 *He proposed to achieve his purpose by use of paper or cardboard which was sold for such purpose, by a binder of bakelite or phenol and formaldehyde, also well known for such use, by hydraulic pressure of 800 pounds and steam heat, followed by cooling and then by baking in an oven at high heat and low pressure. There was indeed nothing new in O'Conor's invention but the two-step of pressure and heat, cooling and baking. If this two-step process was new, and the estoppel requires us to hold as against O'Conor that it was, his assignee had a right to claim the application of it as new not only to flat articles of composition but also to nonplaniform articles as in the eleventh and twelfth claims for though O'Conor had not made such a claim, his original specification foreshadowed it as reasonable. In view of the art, however, it is very clear that the eleventh and twelfth claims must be read to include as an [5] We have been speaking of the application of estoppel in the assignment of patents after they have been granted and their specifications and claims have been fixed. The case before us, however, concerns assignment of an invention and an inchoate right to a patent therefor before the granting of it which, after the assignment at the instance of the assignee, ripened into a patent. Section 4895 of the Revised Statutes (Comp. St. § 9439) authorizes the granting of a patent to the assignee of the inventor. The assignment must be first entered of record in the Patent Office and in all such cases the application must be made and the specification sworn to by the inventor. It is apparent that the scope of the right conveyed in such an assignment is much less certainly defined than that of a granted patent, and the question of the extent of the estoppel *against the assignor of such an inchoate right is more claimed, the two-step process. Without this, difficult to determine than in the case of a pat-there was nothing new in them in the field ent assigned after its granting. When the assignment is made before patent, the claims are subject to change by curtailment or enlargement by the Patent Office with the acquiescence or at the instance of the assignee and the extent of the claims to be allowed may ultimately include more than the assignor intended to claim. This difference might justify the view that the range of relevant and competent evidence in fixing the limits of the subsequent estoppel should be more liberal than in the case of an assignment of a granted patent. How this may be, we do not find it necessary to decide. We can well be clear, however, that if it is proper to limit the estoppel available for an assignee after patent as against his assignor by reference to the state of the art, a fortiori is such ref erence relevant where the estoppel is sought by the assignee before patent. In the light of this conclusion, we must now turn to the facts to which it should be applied. [6] The art which O'Conor entered was that of a composition of materials for insulating purposes, of leaves of fibrous material like paper superposed one on another and united by an adhesive binder coating the leaves, subjected to heat and pressure and hardened into a compact mass and rendered capable of high resistance to the electric current. In the specification of his patent he disclosed his idea of the defect of the then art, which he proposed to remedy by his process, as follows: "Heretofore insulation material such as cardboard composed of layers of paper glued to essential element of the combination therein to which they applied. The eleventh and twelfth claims were made But it is by the company as assignee after O'Conor "The process of manufacturing insulating ma- *355 This was promptly rejected by the Patent Office as it must have been in the then state of the art. It was so absurdly broad and all inclusive as almost to *indicate that it was made to be rejected. O'Conor's signature to such a claim under the circumstances of course does not estop him when in fact it was not allowed, and certainly should not of the eleventh and twelfth claims when as be used to bolster up a broad construction we have said the state of the art must limit them. We are clear then that the estoppel of the eleventh and twelfth claims against O'Conor does not extend to a single step process such |