Vas-Cath, Inc. v. Mahurka (JWB)

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The Case

  • Federal Court of Appeals: Vas-Cath (Plantiffs-Appellees) and Mahurkar (Defendants-Appellants)
  • Mahurkar appeal from a 9/12/1990 partial final judgment of District Court of N. Illinois granting partial summary judgment to Vas-Cath, declaring Mahurkar’s two patents (‘329 and ‘141) invalid
  • district court concluded that none of the twenty-one claims of the two utility patents was entitled to the benefit of the filing date of Mahurkar's earlier-filed United States design patent application ('081 design application), which comprised the same drawings as the utility patents, because the design application did not provide a “written description of the invention” as required


  • March 8, 1982 Mahurkar filed the ‘081 design application
    • Catheter designed to allow blood to be removed from artery
    • Prior art – concentric circular tubes; Mahurkar – joined semi-circular tubes to a single taper (less puncture area for same quantity of blood)
  • Aug 9, 1982 Mahurkar filed a Canadian Industrial Design application for same drawings plus additional textual descripition
  • Oct 1, 1984 Filed first of two utility patent applications (same drawings as ‘081 design application)
    • ’601 app claimed same filing date as ‘081 design app (called a “continuation”)
  • Nov 30, 1984 ‘081 design application was abandoned
  • Jan 29, 1986 ‘592 app filed, claimed same date as ‘081 design app (called “continuation”)
  • April 1, 1987 both considered to be fully supported by ‘081 design app – given same date
  • June 1988 Vas-Cath sued Mahurkar seeking a declaratory judgment that the catheters it manufactured did not infringe Mahurkar's '329 and '141 utility patents
    • Patents invalid because they did not deserve the filing date of the '081 design application because its drawings did not provide an adequate “written description” of the claimed invention as required by 35 U.S.C. § 112
  • Thus, the question before the district court was whether the disclosure of the '081 design application, namely, the drawings without more, adequately meets the “written description” requirement also contained in § 112, first paragraph, so as to entitle Mahurkar to the benefit of the 1982 filing date of the '081 design application for his two utility patents and thereby antedates Canadian '089

  • District Court ruled that the drawings did not, and were therefore anticipated by Canadian ‘089; patents were invalid


  • Historically, the written description was required before claims were, to distinguish the same from all things before known, and to enable anyone skilled in the art to make and use the same
    • two points of patents: enable artisans to make use of the invention, and to put into public possession what is claimed by it
    • difference between the two: “the description of a single embodiment of broadly claimed subject matter constitutes a description of the invention for anticipation purposes ..., whereas the same information in a specification might not alone be enough to provide a description of that invention for purposes of adequate disclosure....”
  • Importantly: “[I]t should be readily apparent from recent decisions of this court involving the question of compliance with the description requirement of § 112 that each case must be decided on its own facts. Thus, the precedential value of cases in this area is extremely limited”
    • Even so, the “written description” requirement has been maintained throughout: “Although [the applicant] does not have to describe exactly the subject matter claimed, ... the description must clearly allow persons of ordinary skill in the art to recognize that [he or she] invented what is claimed.”
  • While drawings alone may provide a ‘written description’ in some cases, the ‘081 design drawings did not ‘allow practice’ (as the District Court claimed)
    • Did not necessarily show what the invention is
  • The district court stated that “although Mahurkar's patents use the same diagrams, [the claims] contain limitations that did not follow ineluctably [i.e., inevitably] from the diagrams.”
  • Mahurkar’s later patents disclose specific diameter ratios and the ‘081 design app did not
    • proper test is whether the drawings conveyed with reasonable clarity to those of ordinary skill that Mahurkar had in fact invented the catheter recited in those claims, having (among several other limitations) a return lumen diameter substantially less than 1.0 but substantially greater than 0.5 times the diameter of the combined lumens. Consideration of what the drawings conveyed to persons of ordinary skill is essential.
  • we assume that the court applied to them the same erroneous legal standard. Summary judgment was therefore inappropriate as to the remaining claims. Additionally, the possibility that the '081 drawings may provide an adequate § 112 “written description” of the subject matter of some of the claims but not others should have been considered

Class Notes

  • 1981 Mahurkar had a US design application
    • Only has drawings
    • Argument over if this is enough for Section 112 (written description requirement)
  • 1982 Canadian application
  • 1984 US utility patent application
    • Mahurkar wanted to use 1981 filing date for these two patents
    • Otherwise utility patents would be invalid because of Canadian application (printed or described in foreign publication/patent, Section 102)


  • District Court: summary judgment – patent application can’t use 1981 filing date
  • CAFC: there are issues – remanded it
  • Biggest issue: what is covered by ‘written description’ in Section 112?


  • Infringer (Vas-Cath) sued patent holder (Mahurkar) seeking a declaratory judgment – i.e. asking for a preliminary ruling whether or not he infringed
  • Question before DC was whether disclosure in ‘081 design app satisfy written description requirement of 112
  • CAFC rules that sometimes drawings are sufficient, in a case by case basis
  • Disclosure
    • claim supporting disclosure
    • claim anticipating disclosure
  • Drawings from design patent must clearly allow persons of ordinary skill in the art to recognize that they invented it
    • convey to public that the inventor invented the invention