Over the last seven years there has been commotion in Obviousness-type Double Patenting (“ODP”) practice. One of the latest cases to spur a considerable amount of interest is Mitsubishi Tanabe Corp. v. Sandoz, Inc., which is currently on appeal to the Federal Circuit (“CAFC”). While a detailed review of this case is not the intent of this post, as a fair number of practitioners have provided insightful coverage, an historical overview is helpful for framing the decision and issues that need clarification from the CAFC.