USPTO:<p>&gt; Patent infringement is the act of making, using, selling, or offering to sell a patented invention, or importing into the United States a product covered by a claim of a patent without the permission of the patent owner. Further, you may be considered to infringe a patent if you import items into the United States that are made by a patented method, unless the item is materially changed by subsequent processes or becomes a trivial and nonessential component of another product. A person “infringes” a patent by practicing each element of a patent claim with respect to one of these acts. Further, actively encouraging others to infringe patents, or supplying or importing components of a patented invention, and related acts can also give rise to liability in certain cases.<p>If the P&amp;G patent isn&#x27;t valid where the blades are manufactured the manufacturer isn&#x27;t in violation. It falls down to whoever is importing them. If they could sue the manufacturer then getting patents in one place would make them defacto valid everywhere and punish companies for the actions of their customers who they have no control over.