Patent Law Research Guide

The status of a patent may be:  filed, approved, denied, withdrawn, reexamined, reissued or became inactive.

Keep in mind that you can Shepardize or Keycite a patent to turn up cases, litigation documents and related patents.

(Format for shepardizing - shep: patno 6553350)

In an Espacenet search, look at the Legal Events field

Commercial Databases, and Other Places to Look

Patent assignments may be hard to find because assignments are not required to be reported and a patent application might not list an assignee.  Try:

• Searching SEC filings on Edgar or a commercial database to see assignments by companies required to file SEC reports.
• Search case opinions or dockets to try and find litigation over the patent.
• Search UCC filings to see if the patent was used as security.  May have to search broadly by company and date, a search by patent number will not turn up security interests in "all assets" or like wording.  The company must file the UCC filing in the state of incorporation.
• Search news articles to find information about assignments.

Also, try searching for different variations of a company name, or for names of subsidiaries.  The commercial database Derwent tries to eliminate this problem by assigning company codes which can be used to search for a company and its subsidiaries.  However, sometimes subsidiaries or related companies will have different company codes!  

Other commercial databases, such as Questel or Minesoft Patbase also may make searching for a patent owner easier.