Warner-Jenkinson Company v. Hilton Davis Chemical Co. (901422128)

Read for 3/28/11

Reading Notes

• Decided by the USSC in 1997
• Hilton sued Warner for infringement of a 1985 patent for purifying dyes
  • Patent specifies filtration through a porous membrane at pH of 5-9
    • This was specified because examiner found an overlap with an old patent which was above pH 9
• Hilton sued based on doctrine of equivalents
  • District court ruled in Hilton's favor
• Court rejects Warner's argument that the doctrine is inconsistent with the Act of 1952
  • USSC disagrees
  • Court in concerned that the broad application conflicts with holdings that a patent may not be enlarged beyond the scope of its claims
    • To avoid this, apply doctrine individually to each element and not the product/process as a whole
• Warner is wrong to suggest that surrender of subject matter during the patent prosecution establishes a bright line beyond which no equivalents may be claimed
  • Must determine the reason behind the language change
    • In this case it is known why the upper limit was added but not the lower
• USSC reverses and remands
  • Federal Circuit did not consider all requirements of the doctrine
• USSC does not speak the death of the doctrine but does seek to clarify it
• Parties disagree about why the low limit (pH 6) was added
• Jury ruled infringement under the doctrine but awarded only 20% of the damages for lack of intent
  • CAFC affirmed
• Warner argues doctrine is inconsistent with aspects of the Act of 1952
  • Section 112 - specific claims
  • Section 251-252 - reissue process
  • None of these hold enough water
• USSC is concerned the doctrine has become unbounded by patent claims
  • Must be applied to individual elements and not the invention as a whole
• Warner also offered alternative arguments for a more restricted doctrine of equivalents
  • Graver Tank never meant to supersede a well-established limit on non-literal infringement
  • Any surrender, during prosecution, for whatever reason, precludes recapturing subject matter
    • Only if it is to avoid unpatentability does it do this
• Since the reason for the lower limit is unknown, it does not preclude the application of doctrine of equivalents
  • USSC thinks the burden should be placed on the patent holder to establish the reason for an amendment during prosecution
    • If none is given it should be assumed that it was related to patentability
• Doctrine does not require proof of intent
• Warner's final argument is that the doctrine should be limited to equivalents disclosed within the patent
  • Also should be limited to those known at the time of the patent
  • USSC rejects both of these ideas
• USSC agrees with the Federal Circuit that juries should apply the doctrine but they do not decide it here

Infringement

• Considerations for applying doctrine
  • Patent's context
  • Prior art
  • Purpose for which an ingredient is used, etc.
  • Whether a person reasonable skilled in the art would know the interchangeability of an ingredient
• Intent plays no role in the doctrine's application
• Proper time for evaluating knowledge of interchangeability is at the time of infringement, not the patent
• 1952 Patent Act is not materially different from the 1870 Act with regard to claiming, reissue, and the role of the PTO
• Section 112 allows "means" claims
• Prosecuting history estoppel places limits on the doctrine and insulates it from conflict with the Patent Act
• Triple identity test
  • Function served by an element, the way it serves that function, and the result thus obtained
  • Good for mechanical but not other products and processes
• Insubstantial differences test
  • Offers little guidance to what is insubstantial

Concurring judges

• Have to be careful that this new presumption does not unfairly discount the expectations of a patentee who had no notice of such a presumption at the time of patent prosecution