I want to implement, in my app, a technique that has been patented in the USA. I live in Bulgaria. Do I need permission from the patent owner?

  • Do you plan to make your app available worldwide (eg on the net) or just in Bulgaria? And (relevant in practice though not in theory) do you plan to charge for your app or just give it away? Dec 3, 2018 at 11:01
  • @TimLymington: Worldwide. And I'm giving the app away for free so far, but I may start charging for it in the future. Dec 3, 2018 at 17:12

2 Answers 2


Bulgaria is one of many countries in which intellectual property can be protected with a single international patent filing, in lieu of a Bulgarian specific filing. In generally, you should assume that any patented idea likely to have international application, such as Internet based software, which is patented in the U.S. is also the subject of international patent protection, unless you specifically know that this is not the case. Virtually all patent lawyers know how to make this filing and most would recommend doing so in this case.

So, yes, it is something you should worry about, and the better practice, by far, would be to obtain permission from the patent owner if the app is likely to have any meaningful commercial value.

Now, if you were sued, there is a good chance that it would be in Bulgarian courts under Bulgarian patent law, which may be somewhat less harsh in some respects like damages awards than U.S. patent law. But, the basis for patent liability for an infringement in Bulgaria would be very similar.

  • The single universal application (PCT application) does start the application process in 140+ countries but to continue the application in any of those countries requires paperwork, fees and engaging a Bulgarian patent practitioner for that country. When it comes choosing counties to enter into the national stage an applicant will make cost/benefit tradeoffs that are very rarely going to suggest pursuing a Bulgarian patent. Dec 6, 2018 at 1:38
  • Also worth recognizing that the fact that the app programmer lives in Bulgaria does not necessarily mean that Bulgarian law applies or is important. For example, if the app distributed via the Apple app store, California law probably governs most of the important questions and the amounts payable to the programmer from the Apple app store could be garnished in the US.
    – ohwilleke
    Dec 6, 2018 at 8:31

Patents are territorial. A U.S. patent gives its owner the right to control who can make, sell, offer for sale, import or use the invention in the U.S. It may be that a counterpart application has been filed or even granted in Bulgaria or other countries.

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