When does a patent begin taking effect, exactly?

And if it takes effect BEFORE being officially approved (which seems strange to me), can the patent's author enforce the patent (for example, through demands to cease or negotiate, and filing of complaints with a professional body like the ACM) without communicating the content of the patent? This would seem to open the door to all kind of abuses.

  • The question is a bit confusing. Demands to cease or negotiate can be made even if there is no patent pending. You can pretty much demand anything you want. And filling complaints, so long as you don't deliberately lie in them, is always something you can do. The status of a patent, unless you lie about it, has on effect on whether you can or can't complain about something that you aren't happy about. Of course, the professional body can decide they don't think the complaint is legitimate, but that's their call and nobody else's. Commented Dec 23, 2022 at 21:45
  • @DavidSchwartz "has on effect" = "has no effect", I presume? (sorry if it sounds bickering, just making sure!). Should not there be negative consequences for filling complaints without having the information to back them up, to prevent people from filling complaints at random?
    – J..y B..y
    Commented Dec 24, 2022 at 7:31
  • @J..yB..y I'm not sure I follow you. Are you suggesting the complaint would have a false claim or just be missing information to back up the true claims that it makes? It's common for a complaint to be based on just what the person complaining knows and be based on reasonable suspicion. Generally, the purpose of a complaint is to start an investigation. (Deliberately lying or withholding relevant information, of course, is not good.) Commented Dec 24, 2022 at 22:08
  • @DavidSchwartz Maybe I am just confused about what "reasonable suspicion" covers.
    – J..y B..y
    Commented Dec 25, 2022 at 6:45

2 Answers 2


Patents become enforceable when granted, not before.

However there is something called provisional rights (absolutely nothing to do with provisional applications). In the US, under 35 USC 154(d), if a claim in a published application is “substantially identical” to a claim that eventually issues, a patent owner can get damages of at least a reasonable royalty on units produced between the publication and notice and the issue date. Enforcement on this must await the granting of the patent.

The infringer must have actual notice of the published application. It is rarely invoked see this article.


An accusation against you to ACM should have details stating what you are accused of. If not, then ACM should reject the accusations. If yes, ACM should tell you what you are accused of. If someone accuses you of something that they know you haven't done (like being in violation of a patent that doesn't exist), that might be libel, and you'd need a lawyer.

If I had a patent application and it was still pending, I believe it is legally fine for you to violate the patent now, but it would be risky, because once the patent is accepted, you would be in trouble. Now I might believe that violating the patent is illegal while it is still pending, and I might accuse you of doing something that I reasonably believe is illegal, and then making the accusation would be wrong but legal. If I haven't even applied for the patent, that's different.

Now if I accuse you legally, and then refuse to provide any evidence, that doesn't make the accusation illegal, but it makes it very weak. For example ACM should reject such an accusation, even if it was true (because they cannot know whether it is true or not). If you sued me for libel, and I still refused to show the evidence, the judge would be allowed to conclude that the evidence doesn't exist and judge against me in the libel case.

PS. The question you see is only vaguely related to the one I replied to.

  • 2
    if you did whatever you do before the patent is filed for, you are actively making the other patent void as prior art.
    – Trish
    Commented Dec 22, 2022 at 11:22
  • 1
    @Trish Only if you published what you were doing. It's my understanding that someone can patent your business secret and then enforce the patent against you (if they find out that you are infringing it, that is).
    – Nobody
    Commented Dec 22, 2022 at 19:33
  • 1
    @nobody not completely correct as there is a prior users right. But that has limitations
    – DonQuiKong
    Commented Dec 22, 2022 at 20:06
  • @DonQuiKong Is that right based on an international treaty, or a US-American peculiarity?
    – Nobody
    Commented Dec 22, 2022 at 20:37
  • 1
    @nobody neither I think. It's something that's present in many national patent laws, possibly with certain differences. But it's nothing to rely on, more of a last resort kind of defense.
    – DonQuiKong
    Commented Dec 23, 2022 at 12:01

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