While European countries carved out an exception for methods of treatment of the human or animal body by therapy, surgery and diagnostic methods practised on the human or animal body (Article 52(4) European Patent Convention (EPC) 1973 (later confirmed in Article 53(c) EPC 2000)), no legislative change dealing with medical methods/procedures occurred in the United States until 1996. However, the Board of Patent Appeals of the United States Patent Office (USPTO) (BOPA) and the courts, namely, the Federal Circuit and the Supreme Court of the United States (Court), did have occasion to consider the issue of patent protection for methods of medical treatment. This book examines the scope of patent protection for methods of medical treatment and genetic diagnostic methods in the United States. Since the question of patent protection has not been finally decided legislatively, the issue is still a live one for the courts in the United States. The jurisprudence considered will mainly examine the central issue of whether medical and genetic diagnostic methods are patent-eligible under section 101 of the Patents Act. An in-depth consideration of the issue is important in light of the continued uncertainty medical patents might have on public health, investment by pharmaceutical companies in research and development, and the impact that uncertainty might have on medical and veterinary practitioners.