Field of use

A field-of-use limitation is a provision in a patent license that limits the scope of what the patent owner authorizes a manufacturing licensee (that is, a licensee that manufactures a patented product or performs a patented process) to do in relation to the patent, by specifying a defined field of permissible operation or specifying fields from which the licensee is excluded. By way of example, such a license might authorize a licensee to manufacture patented engines only for incorporation into trucks (the "truck field"), or to manufacture such engines only for sale to farmers (the "field of distribution to farmers").

The doctrine does not apply to a patent owner’s sale (or its licensee's sale) of a product to a customer that imposes a restriction on what the customer may subsequently do with the product. Such sales are governed by the exhaustion doctrine.