Holding that purchaser confusion is the "primary focus" and, in case of goods and services that are sold, "the inquiry generally will turn on whether actual or potential `purchasers' are confused"
Stating that "[a]s to strength of a mark . . . [third-party] registration evidence may not be given any weight . . . [because they are] not evidence of what happens in the market place"
In University of Notre Dame Du Lac v. J.C. Gourmet Food Imports Co., 703 F.2d 1372, 1376, 217 USPQ 505, 509 (Fed. Cir. 1983), the court added that section 2(a) embraces concepts of the right to privacy which may be violated even in the absence of likelihood of confusion.