Talk:Graver Tank & Mfg. Co. v. Linde Air Products Co. 339 US 605 (1950)

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Maura

3. The doctrine of equivalents is founded on the theory that, if two devices do the same work in substantially the same way and accomplish substantially the same result, they are the same, even though they differ in name, form or shape. Pp. 339 U. S. 608- 609.

4. In determining equivalents, consideration must be given to the purpose for which an ingredient is used in a patent, the qualities it has when combined with other ingredients, the functions which it is intended to perform, and whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was. P. 339 U. S. 609.

But courts have also recognized that to permit imitation of a patented invention which does not copy every literal detail would be to convert the protection of the patent grant into a hollow and useless thing. Such a limitation would leave room for -- indeed, encourage -- the unscrupulous copyist to make unimportant and insubstantial changes and substitutions in the patent which, though adding nothing, would be enough to take the copied matter outside the claim, and hence outside the reach of law. One who seeks to pirate an invention, like one who seeks to pirate a copyrighted book or play, may be expected to introduce minor variations to conceal and shelter the piracy. Outright and forthright duplication is a dull and very rare type of infringement. To prohibit no other would place the inventor at the mercy of verbalism, and would be subordinating substance to form. It would deprive him of the benefit of his invention, and would foster concealment, rather than disclosure, of inventions, which is one of the primary purposes of the patent system.

Union Paper-Bag Machine Co. v. Murphy, 97 U. S. 120, 97 U. S. 125. The doctrine operates not only in favor of the patentee of a pioneer or primary invention, but also for the patentee of a secondary invention consisting of a combination of old ingredients which produce new and useful results, Imhaeuser v. Buerk, 101 U. S. 647, 101 U. S. 655, although the area of equivalence may vary under the circumstances

In its early development, the doctrine was usually applied in cases involving devices where there was equivalence in mechanical components. Subsequently, however, the same principles were also applied to compositions, where there was equivalence between chemical ingredients. Today the doctrine is applied to mechanical or chemical equivalents in compositions or devices

What constitutes equivalency must be determined against the context of the patent, the prior art, and the particular circumstances of the case. Equivalence, in the patent law, is not the prisoner of a formula, and is not an absolute to be considered in a vacuum. It does not require complete identity for every purpose and in every respect. In determining equivalents, things equal to the same thing may not be equal to each other, and, by the same token, things for most purposes different may sometimes be equivalents. Consideration must be given to the purpose for which an ingredient is used in a patent, the qualities it has when combined with the other ingredients, and the function which it is intended to perform. An important factor is whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was.

It is difficult to conceive of a case more appropriate for application of the doctrine of equivalents. The disclosures of the prior art made clear that manganese silicate was a useful ingredient in welding compositions. Specialists familiar with the problems of welding compositions understood that manganese was equivalent to, and could be substituted for, magnesium in the composition of the patented flux ,and their observations were confirmed by the literature of chemistry. Without some explanation or indication that Lincolnweld was developed by independent research, the trial court could properly infer that the accused flux is the result of imitation, rather than experimentation or invention. Though infringement was not literal, the changes which avoid literal infringement are colorable only. We conclude that the trial court's judgment of infringement respecting the four flux claims was proper, and we adhere to our prior decision on this aspect of the case. Affirmed.


Courtney

2. The essence of the doctrine of equivalents is that one may not practice a fraud on a patent.

3. The doctrine of equivalents is founded on the theory that, if two devices do the same work in substantially the same way and accomplish substantially the same result, they are the same, even though they differ in name, form or shape. Pp. 339 U. S. 608- 609.

4. In determining equivalents, consideration must be given to the purpose for which an ingredient is used in a patent, the qualities it has when combined with other ingredients, the functions which it is intended to perform, and whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was. P. 339 U. S. 609.

At the outset it should be noted that the single issue before us is whether the trial court's holding that the four flux claims have been infringed will be sustained. Any issue as to the validity of these claims was unanimously determined by the previous decision in this Court, and attack on their validity cannot be renewed now by reason of limitation on grant of rehearing. The disclosure, the claims, and the prior art have been adequately described in our former opinion and in the opinions of the courts below. In determining whether an accused device or composition infringes a valid patent, resort must be had in the first instance to the words of the claim. If accused matter falls clearly within the claim, infringement is made out, and that is the end of it.

What constitutes equivalency must be determined against the context of the patent, the prior art, and the particular circumstances of the case. Equivalence, in the patent law, is not the prisoner of a formula, and is not an absolute to be considered in a vacuum. It does not require complete identity for every purpose and in every respect. In determining equivalents, things equal to the same thing may not be equal to each other, and, by the same token, things for most purposes different may sometimes be equivalents. Consideration must be given to the purpose for which an ingredient is used in a patent, the qualities it has when combined with the other ingredients, and the function which it is intended to perform. An important factor is whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was.

A finding of equivalence is a determination of fact. Proof can be made in any form: through testimony of experts or others versed in the technology; by documents, including texts and treatises; and, of course, by the disclosures of the prior art.

The question which thus emerges is whether the substitution of the manganese, which is not an alkaline earth metal, for the magnesium, which is, under the circumstances of this case, and in view of the technology and the prior art, is a change of such substance as to make the doctrine of equivalents inapplicable; or, conversely, whether, under the circumstances, the change was so insubstantial that the trial court's invocation of the doctrine of equivalents was justified.

Nevertheless it invoked the judicial "doctrine of equivalents" to broaden the claim for "alkaline earth metals" so as to embrace "manganese." On the ground that "the fact that manganese is a proper substitute . . . is fully disclosed in the specification" of respondent's patent, it concluded that "no determination need be made whether it is a known chemical fact outside the teachings of the patent that manganese is an equivalent. . . ."

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.