This monograph, published as volume 20 in the Max Plank Institute’s series entitled International Review of Industrial Property and Copyright Law (also known as “IIC”), is one of the studies commissioned by the European Patent Organization pursuant to a mandate issued at the Intergovernmental Conference of the member states of the European Patent Organization held from June 24- 25, 1999, on the reform of the patent system in Europe to examine whether European patent law should provide a so-called “pre-filing grace period.” The central requirement for patentability that is common across the patent systems of the world is the requirement of novelty over the prior art – to be patentable, the subject matter of the patent must not have been in the prior art. But, not every patent system in the world defines the scope and content of the prior art in the same way. More specifically, the pre-filing grace period is one major area in which the patent systems of the world substantially diverge when determining what is treated as prior art. For example, in the United States patent system, disclosure of an invention by the inventor does not destroy patentability if it is made within one year before the patent application was filed. Such a disclosure is not treated as being within the prior art. In contradistinction, such disclosure may destroy patentability under the European Patent Convention (“EPC”). It may be treated as being within the prior art.