How to deal with a warning letter asserting an infringement (of patent
right)
You might receive a warning letter from any other party asserting that your product infringes such other parties’ patent rights. In that case, it is important that you do not panic and try to take a businesslike approach. The first step we recommend is to review the contents of the warning letter and promptly consult with a lawyer or a patent attorney. The following are the steps and measures which may be taken to deal with a warning letter.
1. Check if the asserted patent right really exists
You may make investigations on the Patent Gazette, Patent Register, History Record etc. to confirm the existence of the asserted patent right as well as its current status. In particular, you should check if the patent right as the basis of the warning letter has really been registered, if the patent right may have lapsed due to, for example, failure to pay patent fees, or if the other party is really the patentee.
2. Make an assessment to determine if there is an infringement
You may make an assessment to confirm if your product is covered by the technical scope of the other party’s patented invention. Technical scope of a patent invention means the scope specified in the Claims of the said patent published in the Patent Gazette.
In order to obtain the above assessment, you may request a patent attorney to make the above assessment, or request the Patent Office to issue its advisory opinion. Because such an advisory opinion is the one given by the Patent Office, it is generally respected in legal proceedings, although it does not legally bind the court.
3. Confirm if you have any legitimate right
Suppose you find that the warning can be justified and your product is covered by the technical scope of the other party’s patented invention. Even in that case, if you have any reason for defense (counter-argument), there is a possibility that you may be allowed to continue the manufacture, sale, etc. of your product. For example, if you had started manufacturing your product prior to the filing date of the patent application of the other party’s invention, you may have a prior use right.
4. Conduct a search to find any grounds of invalidity of the asserted patent
If there are any grounds for invalidating the patent asserted by the other party, you can argue that the patent is invalid. For example, to confirm if there are any violation of novelty or inventive step, you may conduct a search to find if there any references regarding the other party’s invention in domestic or foreign literature published before the filing date of the asserted patent. If any grounds of invalidity are found, you may consider taking measures which include filing an invalidation trial against the patent with the Patent Office, using the grounds of invalidity as your defense in a possible negotiation with the other party, etc.
5. Explore the possibility of avoiding infringement
If, after having reviewed the above 1.-4., you conclude that it will be difficult to deny the existence of infringing acts on your side, then you may consider changing the design of your product or discontinuing manufacture and sales of the product in order to prepare for the other party’s future claims for damages. Or you may be able to continue commercializing the product by obtaining a license or other rights through negotiation with the other party.