Why can't I find that patent?

"I busted a mirror and got seven years bad luck, but my lawyer thinks he can get me five." -- Steven Wright, American comedian (b. 1955)

A recurring question from my clients is this … A vendor wants to do business with me, and claims to have a patent pending. Why can’t I find it?

I explain the possible reasons for this.  But, since I am not a patent lawyer, I conclude by referring them to the following very helpful site.

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How Come I Cannot Find Patent Pending Info?
Posted on Sep 30, 2011 by attorney Danton Mak
This is not an unusual case: you see a "patent pending" notice on your competitor's product. Yet when you go to the US Patent Office website, you can find no information about the pending patent under the competitor's company name. How come?
Utility patent applications are published generally 18 months from the earliest priority date claimed in the application. Design patent applications are not published at all. Before publication, the file is kept secret and 3rd parties cannot get information on the application. If you do not find anything under the company name, some of the possiblities could be:
1.It has been less than 18 months;
2.The pending application is a design patent application;
3.You looked in the wrong place (there are 2 separate databases, one for issued patents, and one for published applications);
4.It is also possible that the applicant requested no-publication (generally the applicant has to forego foreign filing of the application); or
5.Since all U.S. patent applications are filed in the name(s) of the inventor(s) individually, searching by company name would not produce results if there was no assignment of the application to the company.
One plausible alternative (if you still cannot find the information) would be to order a right to use search. But that is typically quite expensive (thousands of dollars, depending on the technology), and can only be justified for major product lines.
Danton K. Mak
Sheldon Mak & Anderson PC
E-Mail: danton@usip.com
 (Home Page) http://www.usip.com
Source: http://www.avvo.com/legal-guides/ugc/how-come-i-cannot-find-patent-pending-info
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TIP: For other helpful hints, use the Google® search string: why can't i find patent