I have been working with a patent lawyer who drafted my Idea into a patent and filed the patent. The patent went through a normal process of patenting such as search, reviewing by the examiner and finally it was granted (it is EU patent). In all stages, the patent lawyer was helping me and gave me advices to keep my claims and patents and answered the question of examiners. The whole process took me around 4 years and in each step I paid my lawyer.

One year after the time which my patent is granted, I accidentally came up with an older patent (EU and US) which is very similar to my patent idea and it actually claims the same claims as my patent. It is very strange for me why this patent has not been discovered during patent search. Since this patent is 5 years older than mine, it actually can invalidate my patent.

I am wondering if I can sue my patent lawyer for not doing his job well. I appreciate if you guys can give me some clue.

  • I removed the signature as this site decided that the questions should focus on content only, putting the socializing into chat. Find it good, find it bad, that's just how it is, hope you don't mind.
    – user18033
    Mar 2, 2017 at 15:53
  • Agreed with DonQuiKong. But I am curious, this patent you are saying is similar to yours, was not spotted by the EP examiner? EPO's examiners are notoriously known for finding relevant prior art. It was not cited in the search report? Mar 2, 2017 at 16:08
  • It's rare, but it happens. Happened more like 10-15 years ago, when all those "overly-broad" patents became granted that have people scared of the patent system nowadays.
    – user18033
    Mar 2, 2017 at 18:04
  • Also very surprising for me!
    – shane
    Mar 2, 2017 at 22:03

2 Answers 2


Short: you cannot.


If you paid your patent attorney for doing a search prior to drafting your patent (because if not then it wasn't even their job) then obviously they didn't do that to the best possible outcome.


a patent search needs time and time costs money. If you want to find everything then you will find no patent attorney in his right mind that would promise this to you, as it is impossible to find every relevant document. There are always some that even the most thorough search does not turn up.

In every other case, the number of prior art documents found directly correlates with the money you are willing to invest. Would you have stayed with the patent attorney if they had said, hey, give me $30k I'll do 100 hrs of patent search?

Heck, that would cost more than the whole patent process, then I'd rather occasionally lose a patent.

Now all of this is assuming that the document you found is actually that relevant. Maybe it does not teach all limitations contained in your claims?

All that said, it happens. Be happy, it didn't turn up during the examination so you got a patent. Invalidating a patent can take longer than litigation and costs money too, so if the case arises, you might even use your patent. Though that strategy should be carefully evaluated by a professional. And in the end, if the process was perfect and every prior art document was found, there would never be an invalidated patent, invalidation wouldn't even exist.

Another point for you to consider, do you get sued every time somebody finds out that you could have done your job better? Do you want to? For good reasons only screwing up on purpose and sometimes through negligence is punishable. Beeing unlucky or just not beeing the best at your job is not (or not through the law).

  • I'm not sure your short answer is correct, at least in the US. Here, you can sue just about anyone for just about anything. The fact that the EPO examiner didn't find the same prior art argues against it being a gross oversight.
    – Eric S
    Sep 5, 2017 at 15:15
  • @EricShain technically you can sue everyone for everything. The suit getting accepted or winning it is a completely different story - but that's what people normally mean when they ask if they can sue. So that's what I answered, not the literal question, but the real one.
    – user18033
    Sep 5, 2017 at 15:23
  • I guess my rather flippant comment meant that it really depends where you are. I imagine the US the ability to sue is greater since we don't have a loser pays the winner's attorney's fees system.
    – Eric S
    Sep 5, 2017 at 21:54
  • 1
    Consider also that the plaintiff has the burden of proving that the alleged professional malpractice amounted to a violation of the relevant standard of care for that profession, under the circumstances, and (by itself) resulted in some sort of harm to the client's rights or monetary damages.
    – Upnorth
    Sep 6, 2017 at 4:58

While you can sue anyone for just about anything, I do not see any point in trying to recover losses by potentially expending even for money on a lost cause. As an inventor, you should have done your due dilligence to understand the space and art under the classifications in which you were filing. I spent almost an entire year researching prior art (both domestic and international), before filing my first patent (9,635,027). You cannot leave this duty up to your lawyer or whoever is helping in drafting your patent as there is an obvious conflict of interest. There are separate firms that can do prior art searches for you but again YOU have to make yourself an expert.

If this prior art was so obvious, why didn't you find it?

  • What is the obvious conflict of interest? It is pretty common for an attorney to perform a novelty search as well as draft a patent application on the basis of the search. Indeed, I think there is some synergy in doing so, as reviewing the search results helps the attorney understand the field, and draft a better application.
    – Maca
    Dec 25, 2017 at 22:49
  • And any good attorney would do so. The CI is that you are paying them to draft a patent, not to find prior art, if they find tangible prior art that could negate the award of your patent, they may not have your best interest in mind( if they tell you, they lose out on $10k, if they don't, they get to draft your patent and probably make additional money on office actions), hence the CI I was talking about. Dec 25, 2017 at 23:38

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