The European Patent System is facing major challenges resulting from an extension of patentable subject matter leading to an increasing number of patent applications. The European Patent Office has responded with admirable flexibility, but continuing technological change and greater importance ascribed to patents are leading to lengthened examination periods, rising opposition figures and changing behaviour of patent applicants. Stefan M. Wagner analyses problems associated with institutional changes (duration of patent examination and opposition mechanisms), the expansion of the patentable subject matter and organizational challenges for industrial patentees. The study is based on the empirical analysis of large scale datasets on European patents and employs advanced multivariate methods such as semi-parametric and panel-data regression methods.