Are you catching reassigned US patents in your search?

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Update: This post has been edited to reflect that PatBase is jointly operated by Minesoft and RWS Group.

Experienced patent searchers know that searching for patent databases by company name is hard – and I mean really hard.  A company which owns a patent is called the patent “assignee” in the US.  Take a look at our assignee best practices wiki article over on the main Intellogist site to get an overview of some of the obstacles that can trip you up during this kind of search.

One thing that makes patent owner searching so difficult is simply that patents change hands, and when they do, the information published on the patent face is no longer correct.   Another difficulty is that these types of transactions are not always on record at the USPTO.  However, the USPTO does keep a US patent assignment database of all the transactions that they *have* been notified about.   And fortunately, patent search vendors can update their electronic databases with the new assignment information.  (by the way, as far as I know, US reassignment data is the only reassignment data that gets collected and added into commercial patent search products on a regular basis.)

Here is a quick summary of what some major commercial providers do with US reassignment data: