September 28, 2023


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Trying Again: Graver Tank after 70 years

4 min read

by Dennis Crouch

The Supreme Courtroom’s landmark 1950 resolution 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 instances.  The choice established essential guideposts for making use of the doctrine of equivalents (“DOE”), together with consideration of the prior artwork and a concentrate on the substantiality of variations. Whereas courts in the present day 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 approach [to] accomplish considerably the identical end result.”  This has change into often known as the function-way-result or tripartite check.

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 supplies safety from knock-offs which might be solely trivially completely different.  An essential facet of this final result is that its factual depth meant allowed patentees to keep away from abstract judgment and as an alternative continuously 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 modifications. On the similar time, the doctrine has been additional formed and restricted. Courts in the present day 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 will 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 should 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 will in any other case fall beneath equivalents.  In Festo, the Supreme Courtroom offered 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 based mostly on the substantial similarity of the general compositions at concern. Below the usual set forth in Warner-Jenkinson, the Graver Tank evaluation would possible 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 explanation 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 continuously 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 assist software of the doctrine of equivalents typically 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, skilled testimony will present the important thing underlying proof.

On the actual fact/regulation concern, the bulk opinion explains {that a} query is extra prone to be factual in nature when it requires particular scientific information. “Notably is that this so in a area the place a lot relies upon upon familiarity with particular scientific issues and ideas not normally contained within the normal storehouse of data and expertise.” Id. This quote has been cited by various courts in different fields when making an attempt to find out whether or not a selected concern is authorized or factual.

One essential be aware is that this publish focuses on the bulk opinion penned by Justice Robert Jackson.  Justices Hugo Black and William Douglas collectively wrote a dissent concluding that patents ought to be restricted to their literal scope based mostly 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 significantly declaring and distinctly claiming”).

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