Comments on United States Patent Assignment Information

The text below is a copy of an email that I sent the Patent Interference User's Group (PIUG) on November 4, 2003, regarding United States Patent Assignment Information. My email was in response to a chain of emails discussing contents and accuracy of assignment information provided by the commercial database providers.


I am dissatisfied with the possibility that you all may be relying upon commercial databases for assignee due diligence work. You should all keep in mind HOW the assignee information shown on the face of a U.S. patent gets there, WHAT it signifies, and WHAT you should search when checking on title of U.S. patents.

Someone fills out an "Issue Fee Transmittal form" for an allowed patent application. On that form, they write in the name they want to appear on the patent as the Assignee. Sometimes they get that wrong, for a variety of reasons. The name shown as the assignee on an issued U.S. patent is not conclusive evidence that an assignment exists, and it is not conclusive evidence that the entity listed as the assignee is, even at the time of issuance of the patent, the owner of the patent. It is just a name.

On the other hand, the assignment records, which are kept by the USPTO separate from the patent application files, list all assignments and related transfers of interests (primarily security agreements and licenses) for patent properties recorded in the USPTO. If you are interested in knowing the actual current legal assignee and providing persuasive proof a chain of title, the USPTO's assignment records are the best place to look, as opposed to the face of the published patent, or elsewhere. (BUT, see footnote and caveat below.) The assignment database generated by the USPTO shows the information the person filing a copy of the executed assignment writes on the "RECORDATION FORM COVER SHEET." The "RECORDATION FORM COVER SHEET" is the form they are obliged to file along with the copy of the actual executed assignment document. The USPTO's assignment database does not include the actual assignment document. Thus, the USPTO's assignment database and all databases derived from that database only reflect the information copied onto the recordation sheet. I believe that no database provider has copies of the actual assignment documents in an electronic database. The USPTO stores image copies of the actual assignment documents on micro fiche available at the USPTO, indexed by reel/frame. The micro fiche images can be printed and are the best evidence of assignment. Therefore, the best place to do an assignment search in the first instance, is at the USPTO. You can identify allegedly assigned patents by searching the assignment database, and then pull up the ACTUAL assignment documents by the reel/frame associated with each patent number.

When conducting due diligence assignment work, I often see discrepancies in the chain of title that would or should be resolved to perfect the chain of title. For example, I have seen in an assignment chain, the person executing an assignment on behalf of A to B is actually listed as an officer of company C, not company A. (Why did he sign the document? Maybe C owns A and that person thinks that C, not A, owns the patent and is assigning it. Not!) That assignment document would not result in a valid assignment, and B would not have valid title to the patent. The only way to identify that type of defect is to review the actual assignment documents. In any case, any due diligence assignment search should include review of copies of the actual assignment documents.

FOOTNOTE: You may also find security interests that may include patents filed in the state or county secured transactions recording office for the location of the company identified as the assignee. For example, if the assignee has debt, they may have signed a security agreement, general or specific, that may cover some or all IP rights. This is another place to look when conducting a patent assignment due diligence search.

thanks, RICK

Rick Neifeld, Ph.D. Patent Attorney
President, Neifeld IP Law, PC and, LLC
Tel: 703-415-0012
Fax: 703-415-0013
Email: and