An existing patent uses step A, B, C in the independent claim.

My invention inserts a non-obvious step X before step C.

So my invention looks like this. A, B, X, C

Can the existing patent owner sue me for that?

3 Answers 3

  1. yes. they can sue you, uet everyone can sue you, the question is do they have a case, or even more precisely, what are the risk or odds your'e exposed to.
  2. Technically if the method is a comprising method claim (as opposed to consisting) you unlawfully exploit the invention by performing ABC additional steps are not relevant.
  3. The essential question to be asked is are you using the invention of the patent or maybe you create a whole new concept. If it is completely different method, based on another idea that merely share some elements than you maybe not using the invention protected by the patent. If you are just adding to it, improving it, or otherwise use the same idea. than you are not allowed to use your method.
  • Can you fix the word "uet" in the first sentence? Otherwise, I think this is a nice answer.
    – Eric S
    Commented Jun 26, 2019 at 16:18
  • Your point 2 makes much more sense. Thanks Commented Jun 26, 2019 at 22:44

Can the existing patent owner sue me for that?

In a word, yes.

If there is a patent which has a claim specifying the steps A, B and C and your product implements steps A, B and C you infringe. Adding a step X doesn't change that. Now, if X is novel and non-obvious, you might be able to obtain a patent on your improvement, but that doesn't change the infringement. You would have to obtain a license from the owner of the infringed upon patent.

I am not a lawyer and this should not be considered legal advice. As I always recommend, you should consult with an actual patent attorney when determining freedom to operate questions. Relying on internet opinions on hypotheticals is risky.


Technically speaking when a claim term includes the comprising term then any new step included in the method would infringe the patent, But recently in Amgen Inc. v. Sandoz Inc. (Fed. Cir. 2019) Federal circuit affirmed the District court claim construction "washing" and "eluting" steps of the method claimed in the '878 patent (specifically, subparts (f) and (g)) as being separate steps that required the washing step to be performed before the eluting step. Again, under this construction Amgen conceded it could not prevail on infringement because Sandoz performed these steps concurrently with step (e) (regarding application of the refolding solution), and the panel credited Sandoz's argument that the claim "logically requires a series of steps," citing (as did Sandoz) Mformation Technologies, Inc. v. Research in Motion Ltd., 764 F.3d 1392, 1398–1400 (Fed. Cir. 2014) ("a process claim is properly limited to a certain order of steps 'when the claim language, as a matter of logic or grammar, requires that the steps be performed in the order written, or the specification directly or implicitly requires' an order of steps").

In view of the above judgments in order to evaluate infringement of a method claim it is essential to understand what is actually claimed i.e., does the patent claim a method of steps ABC or does the patent claim a method of steps A followed by B followed by C.

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