The written description requirement of 35 U.S.C. §112 ensures that the inventor actually has invented what the patent application claims; the inventor must describe the invention sufficiently to show that he or she is in possession of the invention. The written description requirement derives in part from considerations of patent breadth. By requiring patent applicants to provide a description sufficient to show that they are in possession of the invention, the requirement protects against overbroad claim amendments. Indeed, the Federal Circuit has described one "policy-based rationale" for the description requirement as follows: