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International Patent: How do you search and find?

How and where can I find out; if a product which is all ready on the market in the US has an international patent?

~ France, Europe Union

On this page: 1. Who is in your Patent Family?, 2. International Patents: Fact and Myth, 3. How to perform a WIPO Patent Search 4. Further Foreign Patent Searching

Who is in your Patent Family? {#patent-family}

Groups of patents related to each other are called "patent families". More than one patent may be needed to protect an invention because each country must have its own patent application. Also, inventions can develop over time, and, additional patents can be filed on the same invention and the patents can be related to each other to improve the legal rights. This spider web of patents is called a patent family.

Typically, a patent attorney will search a patent family by accessing a professional patent database. These databases allows for searching the entire patent family, including WIPO patent searching and searching foreign country databases.

This is generally the easiest and cheapest method to discover other patents in the same family. because, the professional databases are accurate and fast to use. The cost for a search by a patent attorney is generally much less than the subscription cost to the professional databases.

Using publicly available tools, a WIPO patent search and foreign patent search can done, but, it will likely miss important information. To find other patents in the family that have been filed directly in foreign countries, you have to search recursively. So, without the support of a professional database, you have to search every patent application number in every other foreign patent database to try to find related patents, where-ever they may be.

International Patents: Myth and Fact {#international-patent}

There is no such thing as an International Patent. Patents are granted by individual countries. The only international patent organization is the World Intellectual Property Organization (WIPO). WIPO only publishes patent applications, called PCT Request. The PCT Request is a request under the Patent Cooperation Treaty. The purpose of this is to extend filing time in foreign countries. The phrase International Patent can sometimes be used to refer to the PCT Request, and, sometimes it means that someone is confused.

How patent protection is created in foreign countries

There are two ways to create patent rights in foreign countries:

  1. File directly in that foreign country and claim priority directly to the first filed patent within one year. No WIPO PCT request is filed, and, a WIPO patent search will not find the patent.
  2. File a WIPO PCT request, wait up to 30 months, then file a foreign patent application.

Finally, it is worth remembering that every country has its own publication rules, and, patents may not be searchable or published, even though they are filed and may someday be granted.

How to do a WIPO Patent Search (PCT Request Search) {#wipo-patent-search}

If you want to do the research yourself, here are some online tools that might help you find related patents in the same patent family. However, if you do not find any patents, that does not mean they do not exist -- it could also mean that you did not have the correct search parameters.

The World Intellectual Property Organization (WIPO) maintains a database of all published Patent Cooperation Treaty (PCT) Requests.

Step 1: Find the US patent application number

If you know the US product, and, you have the US patent application number (usually 8 digits in the form 61/123,456). Go to step 2.

If you have the US publication number, you need to find the application number. You can search the US Patent Publication database to find the application number. A publication number would be in the form US2011/0198187. So the related search query would be:


This should provide you with the Patent Application Number, which is also called the Application Serial Number or just Serial Number. Keep in mind, US patents can also relate to each other, so, you want all application serial numbers for all related US patents.

Step 2: Search PCT Requests at WIPO

Here is the WIPO online patent database. You want to search on the "Priority Number" field. The "Priority Number" is the number assigned by the originating patent office, or, in your case, the number assigned by the US Patent Office as the US Patent application number. So, if the patent application number is 61/304,502, then your search query would be:


This should return the PCT Requests that are related to the US Patent Application.

Step 3: Cross checking your result

You are likely not to have found any patents. In this case, you would be wise to search for the patent by using other criteria that is likely to identify the patent: patent title, inventors, approximate dates of filing, and possibly keywords from the specification.

Further Foreign Patent Searching {#foreign-patent-search}

Finally, you likely will want to do further searching directly in the countries of interest. A PCT Request is not required, and, a patent can claim priority directly to a foreign application. Here is a list of patent databases by country.

Also, a PCT request might issue from any foreign patent, so, again you want to work through all the steps for each and every patent found.

Final Thoughts

Remember, I recommend consulting with a patent attorney to identify patents of interest in foreign countries for two reasons: 1. The patent attorney's database will be more reliable, 2. The patent attorney will be able to quickly identify the potential for rights, even before a specific application is filed in a specific foreign country. That is, the patent attorney can identify the possibility of a future application that claims priority to the original application (in the same patent family).

Good luck and happy patent hunting!

International Patents: Managing Patent Rights outside of US

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