December 3, 2023


Rich Inside You

Wanting Again: Graver Tank after 70 years

4 min read

by Dennis Crouch

The Supreme Courtroom’s landmark 1950 choice in Graver Tank & Mfg. Co. v. Linde Air Merchandise Co., 339 U.S. 605 (1950) is without doubt one of the court docket’s most cited patent circumstances.  The choice established essential guideposts for making use of the doctrine of equivalents (“DOE”), together with consideration of the prior artwork and a give attention to the substantiality of variations. Whereas courts at present emphasize evaluating equivalence on an element-by-element foundation, Graver Tank‘s substantive evaluation stays extremely influential.

Linde Air Merchandise held a patent on welding fluxes utilizing alkaline earth metallic silicates. US Patent No. 2,043,960. Graver Tank’s flux substituted manganese silicate, which was not an alkaline earth metallic. Although Graver Tank’s flux didn’t actually infringe, the Courtroom discovered it carried out “the identical work in considerably the identical method [to] accomplish considerably the identical end result.”  This has turn into often known as the function-way-result or tripartite take a look at.

The choice thus reestablished that merchandise needn’t infringe actually to infringe a patent. Even when the language of a declare isn’t met precisely, the doctrine of equivalents gives safety from knock-offs which might be solely trivially totally different.  An essential side of this final result is that its factual depth meant allowed patentees to keep away from abstract judgment and as an alternative incessantly attain jury.

Over the previous 70 years, Graver Tank’s doctrine of equivalents evaluation has been instrumental in assessing infringement and stays a key instrument for patentees to implement their rights towards insubstantial adjustments. On the similar time, the doctrine has been additional formed and restricted. Courts at present emphasize an element-by-element method slightly than wanting on the product as an entire. Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997). Prosecution historical past estoppel limits the doctrine for claims amended or argued throughout patent prosecution. Id, See additionally, Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002).  And, the doctrine of vitiation precludes a discovering of equivalence when it could successfully get rid of or “vitiate” a declare limitation. See, Freedman Seating Co. v. American Seating Co., 420 F.3d 1350 (Fed. Cir. 2005) and Depuy Backbone, Inc. v. Medtronic Sofamor Danek, Inc., 469 F.3d 1005 (Fed. Cir. 2006).

In Warner-Jenkinson, the Supreme Courtroom reaffirmed the viability of the doctrine of equivalents, however positioned some limitations on its software. Particularly, the Courtroom held that the doctrine have to be utilized to particular person parts of a declare, to not the invention as an entire. The Courtroom additionally held that prosecution historical past estoppel can bar the doctrine of equivalents when an modification or argument throughout patent prosecution surrenders subject material that might in any other case fall beneath equivalents.  In Festo, the Supreme Courtroom supplied extra element on prosecution historical past estoppel (PHE)–establishing a a presumption towards software of the doctrine of equivalents for declare limitations that have been amended throughout patent prosecution for causes associated to patentability.

In Graver Tank, the Courtroom had utilized the doctrine to seek out infringement primarily based on the substantial similarity of the general compositions at challenge. Below the usual set forth in Warner-Jenkinson, the Graver Tank evaluation would probably have in contrast the “alkaline earth metallic silicate” and “manganese silicate” parts particularly to find out their equivalence. Moreover, prosecution historical past estoppel might have precluded equivalence, if the rationale alkaline earth metals have been claimed was to beat a rejection throughout patent prosecution.

The rise of those authorized limitations has given judges instruments to extra incessantly dismiss DOE claims on abstract judgment or JMOL.

Because the chart exhibits above, courts proceed to quote and depend on Graver Tank. The next are typical causes:

  • To help software of the doctrine of equivalents usually and reference the “function-way-result.”
  • To emphasise that minor or insubstantial variations don’t keep away from infringement.
  • To notice that equivalents is a query of reality for the jury to determine slightly than a query of regulation.  Sometimes, knowledgeable testimony will present the important thing underlying proof.

On the very fact/regulation challenge, the bulk opinion explains {that a} query is extra more likely to be factual in nature when it requires particular scientific data. “Significantly is that this so in a discipline the place a lot relies upon upon familiarity with particular scientific issues and ideas not often contained within the common storehouse of data and expertise.” Id. This quote has been cited by a lot of courts in different fields when making an attempt to find out whether or not a selected challenge is authorized or factual.

One essential word is that this put up focuses on the bulk opinion penned by Justice Robert Jackson.  Justices Hugo Black and William Douglas collectively wrote a dissent concluding that patents needs to be restricted to their literal scope primarily based upon the declare language.  The dissent argued that the DOE undermined the statutory requirement for clear patent claims.  See 35 U.S.C. 112(b) (“claims notably stating and distinctly claiming”).

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