Making the Patent Scope Consistent with the Invention : Evidence from Japan

It is a crucial function of patent examination to make the patent scope consistent with the contribution of the invention to the state of the art. We assess this function using newly developed data on the scope of Japanese patent applications and grants. We find that the scope was narrowed in two thirds of the grants, both the incidence and the extent of narrowing increased when the applicant chose broad initial scope and decreased when the quality of the applicant's disclosure of prior art was high, and that important applications experienced narrowing more frequently, as one expects from rational examination