How do I confirm if an United States patent has been filed through the PCT ? Is there a number(cover page) on a granted patent that shows all the countries that the invention are protected in as well ?

2 Answers 2


How do I confirm if an United States patent has been filed through the PCT

A US patent that started as a PCT application and then entered the US system can be detected by looking on the front page for item (21) Appl. No. If the originating application was a PCT application you will see PCT in the application number.

Is there [something] on a granted patent that shows all the countries that the invention are protected in?


Not definitively. But the EPO has something called INPADOC that lists members of a patent family from around the world. It will not necessarily list patents from smaller locations. I just looked up a patent family (with 20+ applications) that I am working on and was surprised to see that it picked up most of not all members of the patent family including one in Taiwan, which, according to WIPO/UN, does not even exist.

To use INPADOC first look the patent you know about up in the EPOs Espacenet. In the example below see the INPADOC patent family box on the left. enter image description here

The next image is of an INPADOC result page.

enter image description here

VIA PCT National Stage

Each country/regional body handles its own patent examination, granting and publishing. Also, keep in mind that the publication of a patent is like publication of a book in that events that occur after its publication are not reflected in its contents. There are databases that can help you. For a PCT application you could look in WIPO's PatentScope for the PCT application. It will have a tab called National Phase. screen shot of PCT application record

At that page you should see a list of the places, if any, that the PCT application entered the national stage. This may not actually include everything because there can be corresponding patent applications to the the PCT application without actually being a national stage of it. For example Argentina is not part of the PCT system and the U.S. has something called a by-pass application. Things can go from a PCT to a regional body like the EPO and then to actual countries in an additional step.

Also, a patent application can be filed in multiple locations without the PCT process. This is done under the Paris Convention, a much older international agreement now managed by WIPO.

national stage list

Looking it up in google patents or The Lens can be a quick way to possibly learn about patents in multiple locations.

  • Great answer. If I could upvote twice, I would.
    – Eric S
    Commented Oct 15, 2019 at 1:24
  • @EricShain - thanks and I just made it much better. I had forgotten about INPADOC an EPO service that attempts to lists worldwide patent families. It is not perfect but I see that it has gotten much better than it was a few years ago.
    – George White
    Commented Oct 15, 2019 at 4:44

• If an US patent has been filed through the PCT, it can be confirmed from the bibliographic details / front page of the US patent which includes the fields like PCT filed, PCT No., 371 Date, 102(e) Date, PCT Pub. No., and/or PCT Pub. Date.

• No, such details are not available on the US granted patent. It can be viewed on WIPO IP portal @ https://patentscope.wipo.int/search/en/search.jsf by entering the corresponding PCT number. Upon clicking the retrieved result, all the related details of PCT number can be obtained, wherein the National phase tab includes the details of all country filing details.

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