381 F.3d 1320 (Fed. Cir. 2004) Cited 71 times 10 Legal Analyses
Affirming conclusion that toothbrush and small hair brush were in same field of endeavor because "the structural similarities between toothbrushes and small brushes for hair would have led one of ordinary skill in the art working in the specific field of hairbrushes to consider all similar brushes including toothbrushes"