Fletcher YoderThe concept of prosecution history estoppel from utility patents applies to design patents as well. Amendments made in response to a restriction for a design patent can result in prosecution history estoppel.
When determining obviousness in a design application, a two-step test is used. First, a primary reference must be identified, this primary reference being “something in existence” that has “basically the same” appearance as the claimed design. Second, other references can be used to modify the primary reference “to create a design that has the same overall visual appearance of the claimed design.”
A factor to be considered in granting a preliminary injunction is the patentee’s likelihood of success on the merits. In assessing this factor, a trial court should evaluate the alleged infringer’s evidence of invalidity as well as the evidence the patentee presents in rebuttal. The inquiry into the obviousness of a design patent is whether the claimed design would have been obvious to a designer of ordinary skill who designs articles of the type involved.