By Kevin E. Noonan — Joint inventorship has been called "one of the muddiest concepts in the muddy metaphysics of patent law" because the "exact parameters of what constitutes joint inventorship are quite difficult to define." Mueller Brass Co. v. Reading Indus., 352 F. Supp. 1357, 1372 (E.D. Pa. 1972), aff’d, 487 F.3d 1395 (3d Cir. 1983). The consequences of an improper (or improvident) determination of inventorship (and the sometime difficulties that can arise when a change of inventorship is delayed until a patent is being asserted at trial) is illustrated in the Federal Circuit’s recent non-precedential decision in Horizon…
