BLACK, J., dissenting. 339 U.S. the Court has heretofore recognized as wise safeguards. See Milcor Steel Co. v. Fuller Co., 316 U. S. 143, 148. One need not be a prophet to suggest that today's rhapsody on the virtue of the "doctrine of equivalents" will, in direct contravention of the Miller case, supra, make enlargement of patent claims the "rule" rather than the "exception." Whatever the merits of the "doctrine of equivalents" where differences between the claims of a patent and the allegedly infringing product are de minimis, colorable only, and without substance, that doctrine should have no application to the facts of this case. For the differences between respondent's welding substance and petitioners' claimed flux were not nearly so slight. The claims relied upon here did not involve any mechanical structure or process where invention lay in the construction or method rather than in the materials used. Rather they were based wholly on using particular materials for a particular purpose. Respondent's assignors experimented with several metallic silicates, including that of manganese. According to the specifications (if these are to be considered) they concluded that while several were "more or less efficacious in our process, we prefer to use silicates of the alkaline earth metals." Several of their claims which this Court found too broad to be valid encompassed manganese silicate; the only claims found valid did not. Yet today the Court disregards that crucial deficiency, holding those claims infringed by a composition of which 88.49% by weight is manganese silicate. In view of the intense study and experimentation of respondent's assignors with manganese silicate, it would be frivolous to contend that failure specifically to include that substance in a precise claim was unintentional. Nor does respondent attempt to give that or any other explanation for its omission. But the similar use of manganese in prior expired patents, referred to in the Court's opinion, raises far more than a suspicion that its elimina 605 BLACK, J., dissenting. tion from the valid claims stemmed from fear that its inclusion by name might result in denial or subsequent invalidation of respondent's patent. Under these circumstances I think petitioners had a right to act on the belief that this Court would follow the plain mandates of Congress that a patent's precise claims mark its monopoly boundaries, and that expansion of those claims to include manganese could be obtained only in a statutory reissue proceeding. The Court's ruling today sets the stage for more patent "fraud" and "piracy" against business than could be expected from faithful observance of the congressionally enacted plan to protect business against judicial expansion of precise patent claims. Hereafter a manufacturer cannot rely on what the language of a patent claims. He must be able, at the peril of heavy infringement damages, to forecast how far a court relatively unversed in a particular technological field will expand the claim's language after considering the testimony of technical experts in that field. To burden business enterprise on the assumption that men possess such a prescience bodes ill for the kind of competitive economy that is our professed goal. The way specific problems are approached naturally has much to do with the decisions reached. A host of prior cases, to some of which I have referred, have treated the 17-year monopoly authorized by valid patents as a narrow exception to our competitive enterprise system. For that reason, they have emphasized the importance of leaving business men free to utilize all knowledge not preempted by the precise language of a patent claim. E. g., Sontag Stores Co. v. Nut Co., 310 U. S. 281, and cases there cited. In the Sontag case Mr. Justice McReynolds, speaking for a unanimous Court, said in part: "In the case under consideration the patentee might have included in the application for the original patent, claims broad enough to embrace petitioner's accused machine, but did not. DOUGLAS, J., dissenting. 339 U.S. This 'gave the public to understand' that whatever was not claimed 'did not come within his patent and might rightfully be made by anyone.'" Id. at 293. The Court's contrary approach today causes it to retreat from this sound principle. The damages retroactively assessed against petitioners for what was authorized until today are but the initial installment on the cost of that retreat. MR. JUSTICE DOUGLAS, dissenting. The Court applies the doctrine of equivalents in a way which subverts the constitutional and statutory scheme for the grant and use of patents. The claims of the patent are limited to a flux "containing a major proportion of alkaline earth metal silicate." Manganese silicate, the flux which is held to infringe, is not an alkaline earth metal silicate. It was disclosed in the application and then excluded from the claims. It therefore became public property. See Mahn v. Harwood, 112 U. S. 354, 361. It was, to be sure, mentioned in the specifications. But the measure of the grant is to be found in the claims, not in the specifications. Milcor Steel Co. v. Fuller Co., 316 U. S. 143, 145, 146. The specifications can be used to limit but never to expand the claim. See McClain v. Ortmayer, 141 U. S. 419, 424. The Court now allows the doctrine of equivalents to erase those time-honored rules. Moreover, a doctrine which is said to protect against practicing "a fraud on a patent" is used to extend a patent to a composition which could not be patented. For manganese silicate had been covered by prior patents, now expired. Thus we end with a strange anomaly: a monopoly is obtained on an unpatented and unpatentable article. Syllabus. COMMISSIONER OF INTERNAL REVENUE v. KORELL. CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE SECOND CIRCUIT. No. 384. Argued February 7, 1950. Decided June 5, 1950. In 1944, an individual taxpayer purchased at a premium price of $121 certain taxable corporate bonds with a face value of $100 which were then callable at $104. Upon payment of $40, each bond was convertible at the option of the holder into a share of common stock which then had a market value of $163. Held: Under § 125 of the Internal Revenue Code, the taxpayer, in his income tax return for 1944, was entitled to deduct, as "amortizable bond premium" on each bond, the difference between the purchase price of $121 and the call price of $104. Pp. 620-628. (a) The callability and convertibility of these bonds did not remove them from the reach of § 125. Pp. 623–624. (b) That the premium may have been paid for the conversion privilege, rather than for a higher rate of interest, did not prevent it from being amortizable under § 125. Pp. 624–628. (c) The term "bond premium" in § 125 means any extra payment, regardless of the reason therefor. P. 627. 176 F. 2d 152, affirmed. The Commissioner of Internal Revenue disallowed respondent's deduction in his individual income tax return of "amortizable bond premium" under § 125 of the Internal Revenue Code. The Tax Court overruled the Commissioner. 10 T. C. 1001. The Court of Appeals affirmed. 176 F. 2d 152. This Court granted certiorari. 338 U. S. 890. Affirmed, p. 628. Arnold Raum argued the cause for petitioner. With him on the brief were Solicitor General Perlman, Assistant Attorney General Caudle, Ellis N. Slack and Oscar H. Opinion of the Court. 339 U.S. Paul L. Peyton argued the cause and filed a brief for respondent. Nat Schmulowitz and Peter S. Sommer filed a brief for Shoong et al., as amici curiae, supporting respondent. MR. CHIEF JUSTICE VINSON delivered the opinion of the Court. The tax consequences of a purchase of convertible bonds are in issue here. In August, 1944, respondent, an individual taxpayer, purchased certain American Telephone and Telegraph Company bonds, each having a face value of $100, at a premium price averaging slightly in excess of $121. Each bond was convertible into a share of common stock, at the option of the bondholder, upon the payment of $40. The market price of the stock was over $163 when respondent made his bond purchases. The bonds were callable prior to maturity date according to a schedule appearing in the indenture; had the corporation given appropriate notice at the dates of respondent's purchases, the bonds would have been redeemed at $104. In his 1944 income tax return, respondent claimed a deduction in excess of $8,600 for amortizable bond premium. He computed his deduction on each bond as the difference between his purchase price, $121, and the call price, $104. This computation is concededly correct if the deduction is allowable. The Commissioner of Internal Revenue, petitioner here, refused to allow any such deduction. His theory was that § 125 of the Internal Revenue Code establishing the deduction for "amortizable bond premium" did not include premium paid for the conversion privilege. A contrary view of the statute was adopted by the Tax Court. 10 T. C. 1001 (1948). The court below affirmed, holding that respondent was entitled to the amortization deduction. 176 F. 2d 152 (1949). We granted certiorari, 338 U. S. 890 (1949), to resolve |