Fletcher YoderThe Federal Circuit holds that the claim recitation “readily installed” is not indefinite, and that an interference fit (in a hearing aid) is equivalent to a threaded joint, ball and socket joint, and adhesive joint for purposes of interpreting means-plus-function claims.
Question of law is presented by issue of whether patentee, having made narrowing claim amendment for substantial reason related to patentability, has successfully rebutted presumption that it has surrendered all territory between original claim limitation and amended limitation, since prosecution history estoppel is equitable in nature, and whether such estoppel applies presents question of law.