• Posts Tagged ‘assignor estoppel’

    Assignor Estoppel is Only a Shield

    by  • February 13, 2013 • patent • 1 Comment

    Here’s a bit of an odd case — too much of a stretch for the court’s taste, but I suppose a hat tip for the try, and the plaintiff got out of it without being sanctioned. The case involves “assignor estoppel.” Assignor estoppel is an equitable doctrine that prevents an assignor of a patent...

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    When an Assignor is Not Estopped

    by  • November 12, 2010 • patent

    Assignor estoppel is an equitable doctrine that precludes the assignor of a patent from later challenging the validity of the patent. The reach of the doctrine is limited, though, as explained in Borgwarner, Inc. v. Honeywell International, Inc.  The patents-in-suit are for a titanium compressor wheel made by investment casting. In mid-2000, Plaintiff BorgWarner...

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