In a previous post, I had covered the basics of patent infringement and how to ascertain literal infringement of a patent claim vis-à-vis all element rule. In this post, I shall be covering the basics of infringement by equivalence and how it is done.
According to the doctrine of equivalence, a product/process is said to be infringing if it performs substantially the same function in substantially the same way to achieve substantially the same result. Now, the question that arises is how to ascertain equivalence.
We have seen that while using the all element rule one has to compare and find all the elements of the claim in the infringing product/process. The doctrine of equivalence comes into play when there are differing elements in the product/process. The question to be asked while using the equivalence doctrine is:
Whether the differing element of the infringing product is equivalent to the element present in your client’s claim?
How to ascertain equivalence?
An old test of ascertaining equivalence is to look into the substance of the invention. This is a traditional test which has evolved from common law jurisprudence. The Novartis case also used this method i.e. looking into the pith and substance of the invention. Apart form this test, the other tests are:
- Function, Way, Result Test
- Obviousness Test
Function, Way, Result Test
If the differing element performs substantially the same function in substantially the same way to produce substantially the same result.
Step1: Determining the function of the particular element of the infringing product.
Step2: Comparing the function of the particular element to that of the element of your client’s claim.
Step3: Analysing whether the functions of both the elements are same or not.
Step4: Analyse whether the way in which the function is being carried on is the same in both or not.
Step5: Analyse whether or not they yield the same result.
If the answer to steps 3, 4, and 5 is yes, then there is infringement.
The question to be asked is
Would a Person Skilled in the Art (PSITA) replace the infringing element with the particular element of your client’s claim?
If the answer is yes, then there is infringement
The issue with the obviousness test is how should one determine who a PSITA is? I shall be covering this question with respect to obviousness analysis in a subsequent post.
Image from here.