How can we estimate Infringement under the Doctrine of Equivalents (DOE)?
You are still infringing the patent, even if you are not using the same features of any patent under the Doctrine of Equivalents. When it is about patent infringement, people generally consider literal infringement. However, it cannot be the case every time. It is possible that if you are not infringing under literal infringement, still you fall in to the scope of any patent under doctrine of equivalents, which means if you have changed one element of patent with another and if it has the same function and work with the same mechanism and produce same results, it is falling under Doctrine of Equivalents (DOE). How that is analysed is described in more details in this article for a clear understanding of the Doctrine of Equivalents (DOE).
When an accused product is not exactly similar of claim literally, it may nevertheless be found to infringe a claim if there is
“similarity” between the elements of the concerned process or product and the granted claims covering elements.
In the United States, the legal text from Graver Tank & Manufacturing Co. v. Linde Air Products Co., (1950) and Warner-Jenkinson Co. v. Hilton Davis Chem. Co. (1997) have mentioned different tests to determine the
“equivalence” by using
“Function-Way-Result (FWR) Test” and
“Insubstantial Differences”.
The
“Function-Way-Result (FWR) Test” provides three steps to determine the “equivalence”:
- The “Function” test checks if the accused object performs substantially the same function as the claimed invention;
- The “Way” test checks whether the accused product or process works in a substantially similar manner as the claimed element and
- The “Result” test evaluates if the accused product or process produces substantially the same result as the claimed element.
The other
“Insubstantial Differences Test” checks if the accused object is substantially different from the claimed invention or element.
While the
“Function-Way-Result (FWR) Test” is used in both chemical and mechanical invention cases, the United States Court of Appeals for the Federal Circuit (CAFC), recently in
Mylan Institutional LLC v. Aurobindo Pharma Ltd. (Fed. Cir. 2017) emphasized that for chemical cases the “Insubstantial Differences Test” should be preferred over the application of the “Function-Way-Result (FWR) Test”.
While the tests described above, provide clarity over how the analysis of infringement under the Doctrine of Equivalents needs to be performed, the analysis does not end there. There are certain set of legal steps that need to be performed in order to bring depth as well as assurance to the DOE analysis.
One legal step is to check the specification of the patent in question for DOE analysis discloses the elements of the accused product or process. If specification specifically discloses the elements of the accused product or process but does not claim, then under
“disclosure dedication rule” those elements are considered to be deemed dedicated to the public. The patentee then under “disclosure dedication rule” cannot enforce those disclosed but unclaimed elements under DOE.
However, it is worth noting that in PSC Computer Products v. Foxconn International, Inc., 355 F.3d 1353 (Fed. Cir. 2004), CAFC clarified that the element in question must be disclosed in a manner to allow a person of ordinary skill in the art (PHOSITA) to identify it as an unclaimed subject matter. The unclaimed subject matter must be identified as a similar or equivalent to a claimed elements.
The other legal step is the study of the prosecution history and explores if a
“Prosecution History Estoppel” is applicable. “Prosecution History Estoppel” restricts the broader application of the doctrine of equivalents by barring an equivalents elements for claims which were relinquished when a patent claim was narrowed down to overcome any novelty objection during prosecution. Prosecution history estoppel can occur in any of the two situations mentioned below:
- “Amendment-based Estoppel” applies if the claimed was narrowed by way of an amendment to a claim or
- “Argument-based Estoppel” applies if the claim scope was surrendered through argument to the patent examiner.
CAFC recently reiterated in UCB, Inc. v. Watson Laboratories Inc. (Fed. Cir. 2019) citing Bayer Aktiengesellschaft v. Du-phar Int’l Research (Fed. Cir. 1984) that if the subject matter was objected by examiner by way of a restriction requirement then generally restriction requirement responses do not bring Prosecution History Estoppel.
Next step is checking for
“ensnarement”. If prior art ensnares/encompasses the elements of the accused product or process then the same cannot be subjected to infringement under DOE. Whether the prior ensnares or not is checked by performing
“hypothetical claim analysis”.
The “hypothetical claim analysis” is a two-step process:
- Construction of hypothetical claims that covers the elements of the accused product or process literally.
- Prior art is assessed to check if the hypothetical claims are patentable over the prior art.
The other important aspect to consider is
“doctrine of vitiation”. Based on Akzo Nobel Coatings, Inc. v. Dow Chem. Co. (Fed. Cir. 2016), a patentee will not be able to raise the equivalents under DOE if it renders a claim scope inconsequential or ineffective.
Finally, it is worth considering aspects associated with
“foreseeability”. In
Ring & Pinion Service Inc. v. ARB Corp. (Fed. Cir. 2014) CAFC held that there is not, nor has there ever been, a foreseeability limitation on the application of the doctrine of equivalents. Excluding similar elements that were foreseeable at the time of filing of the patent would directly conflict with prior Supreme Court and Federal Circuit case considering that known interchangeability favours infringement under the doctrine of equivalents.
Recently, CAFC in UCB, Inc. v. Watson Laboratories Inc. (Fed. Cir. 2019) provided further clarification on “foreseeability”. While Ring & Pinion held that foreseeability at the time of claim drafting is not a per se bar to the application of the doctrine of equivalents. But, at the same time, Ring & Pinion does not foreclose consideration of foreseeability of an asserted equivalent as one factor that may, in some cases, help show that the facts cannot support infringement under the doctrine of equivalents.
In Europe, recent Supreme Court of the United Kingdom in Actavis v. Lilly [2017] UKSC clarified that the correct approach for infringement analysis is two steps inquiry and thus bringing the question of the doctrine of equivalents into consideration overstepping earlier conservative analysis standard prescribed by Kirin-Amgen v. Hoechst Marion Roissel [2004] UKHL.
- Whether the accused product or process infringes as a matter of normal interpretation (literal infringement) and
- Whether the accused product or process infringes because it varies from the invention in ways which are immaterial (doctrine of equivalents).
While the standard that is set forth in Article 69 of European Patent Convention (EPC) remains same for all member states of EPC, there is a difference in how Article 69 EPC is interpreted in various member states. What is considered infringement in one state may or may not be infringement in other member states.
In
Ravi Kamal Bali v. Kala Tech, Bombay High Court [2008], the DOE arguments were presented by the patentee in a preliminary injunction. Still, the jurisprudence in India on DOE is in its infancy stage. We will have to wait and see how the courts interpret the question of Doctrine of Equivalents (DOE)
Determination of whether a modification practised infringes a claim of a valid patent under the doctrine of equivalents requires a thorough analysis of the facts of a particular case as well as righteous interpretation of the laws and regulations associated of a particular jurisdiction.
We at EXCELON IP advise our clients to seek our legal advice on issues of Freedom-To-Operate (FTO) under the doctrine of equivalents at an early stage so as to develop a legally untenable non-infringement strategy. It is always better to have knowledge of upcoming hurdles well in advance to calculate risk vs reward.
