Skechers has filed a series of counterclaims challenging the validity of a dozen design patents held by Nike in response to two separate lawsuits filed against it last autumn. Nike had accused Skechers of imitating its Air Vapor Max and Air Max 720 sneakers in one suit, and of infringing on its design patents with two Skech-Air models in the other. Skechers has now responded by asking a court to invalidate all the design patents. It also categorically denied allegations that it is asking any employees to make exact copies of competitors' shoes. Both Nike and Adidas have accused the company of “Skecherizing” some popular designs and styles, copying some of their key elements.