Royalty stacking

"Royalty stacking refers to situations in which a single product potentially infringes on many patents, and thus may bear multiple royalty burdens. The term “royalty stacking” reflects the fact that, from the perspective of the firm making the product in question, all of the different claims for royalties must be added or “stacked” together to determine the total royalty burden borne by the product if the firm is to sell that product free of patent litigation." Mark A. Lemley & Carl Shapiro, "Patent Holdup and Royalty Stacking," 85 Texas L. Rev. 1991, 1993 (2007).