Why is my invention infringing?
Why is my invention infringing even though I received a utility patent?
The legal test for whether invention-1 infringes on invention-2 is whether invention-1 contains elements identical or equivalent to each claimed element of invention-2.
If invention-1 contains elements identical to invention-2, then there is literal infringement.
If invention-1 contains elements equivalent to invention-2 then the Doctrine of Equivalents applies. This is analogous to the legal concept of obviousness, but it is analyzed in a much different way. Under the
Doctrine of Equivalents, equivalence is determined by either:
(1) the function-way-result test, or
the accused product infringes if it performs substantially the same function, in substantially the same way, and with substantially the same result
(2) the insubstantial differences test
an element in the accused device is equivalent to a claim limitation if the only differences between the two are insubstantial
“If I have a patent that means that the elements of my claimed invention are not equivalent to another patent, thus cannot infringe on another’s patent, right”?…
“If my patent is found to be infringing, does that invalidate my patent”?…
The reasoning for these answers is articulated in the following court case: Siemens Med. Solutions USA, Inc. v. Saint-Gobain Ceramics & Plastics, 637 F.3d 1269 (Fed. Cir. 2011). There are four reasons why the answers to the above questions are counter to what one might think.
1. Equivalence (infringement) occurs where differences between a patented invention and a suspected infringing invention are insubstantial. Obviousness (invalidating) occurs where the combinations/modifications making up the differences are deemed to be obvious to one skilled in the art.
2. Equivalence is determined at the time of the alleged infringement, whereas obviousness is determined at the time the claimed invention was made.
3. The burden of proof in an infringement case is measured by a preponderance of the evidence, which is a lower standard than that of invalidating an issued patent having a burden of proof of clear and convincing evidence.
4. The scope of a claim of an infringing patent can cover a broad range, but if the actual infringement occurs only within a specific section of that range, then it will not invalidate the entire patent.
Keep in mind that the above principles of law only regard utility patents. Design patents are analyzed differently. Furthermore, much of this law is case law, which varies from one Federal District/Circuit to another.