In Contessa Food Products Inc v. Congara Inc. the Court of Appeals for the Federal Circuit (CAFC) was faced with the question of what was the proper scope of protection for a design patent which depicted a serving tray with shrimp. The District Court for the Central District of California had granted summary judgment in favor of the patent owner largely because the arrangement of shrimp on the defendants tray was substantially the same as that shown in the design patent, which arrangement the court thought was the point of novelty of the design. The Federal Circuit reversed this holding on the ground that the district court had not properly considered the design of the bottom of the trays.

The appeal court pointed out that the drawings in the design patent included the bottom of the tray and that the patentee had not availed himself of the opportunity to show the features of the bottom of the tray in broken lines so as to show that such features were not essential to what was claimed. The district court had discounted the importance of the bottom of the trays as being not visible or at least partially obscured at the point of sale. In doing so it had noted that the nineteenth century Supreme Court which provides the basis for the "ordinary observer" test used in design patent infringement analysis had referred to such an observer being confused as to which of two products to purchase. The appeal court held that confining consideration to what was visible at the point of sale was a reversible error. The district court should not have confined its consideration to the time of sale but should have considered whether the ornamental features of the tray's bottom were of concern at any time during the normal use of the product. The reference in the Supreme Court's test to a purchaser was simply to define the standard of scrutiny to be given in determining whether the alleged infringement was similar to the patented design, not to define the point in time at which such a comparison should be made.

The CAFC set out the proper test to be applied as follows:

One must compare the ornamental features of the patented design, as shown in all the drawings, to the features of the alleged infringing product visible at any time during normal use of the product and assess if the resemblance at such point is such as to deceive... an ordinary observer, giving such attention as a purchaser usually gives "inducing him to purchase one supposing it to be the other." ... [T]he "ordinary observer" analysis is not limited to those features visible at the point of sale, but instead must encompass all ornamental features visible at any time during normal use of the product.