Revision with unchanged content. This book explores the effect of marginal changes in the exclusivity environment, on research efforts of firms involved in drug R&D and production in the US. Exclusivity here refers to the IP environment and marketing regulations of the Food and Drug Administration (FDA), both of which determine the exclusive marketing period and appropriation allowed for drug research. In the US, drugs have to go through a long approval process with the FDA before marketing. Several legal decisions were instrumental in recognizing weak links in this process over 1984 to 2003 when key statutory amendments were passed. This book starts by providing some background on the IP and drug regulation in the US. Next, using the event study method, the reaction of firms categorized into three groups- Pharmaceuticals, Biotechs and Generics are analyzed as a consequence of some precedent-setting patent and regulatory cases. Cases returning significant abnormal returns are then considered in further analyzing the research behavior of pharmaceutical and biotech firms. This book is addressed to anyone interested in the drug research appropriation debates in the US including patent law and public policy experts.