[Rachel Moodie and Bernard Chao] Abstract: Drug prices in the United States are higher than in other countries. Generic drugs offer one path to lower these prices. The Biologics Price Competition and Innovation Act ('BPCIA') was passed in 2010 to promote the entry of biosimilars, generic versions of a new class of biologic drugs. These drugs have proven to be effective at treating a variety of illnesses including various autoimmune diseases and cancers. But to date, few biosimilars have entered the U.S. market. Patent thickets covering biologic drugs may be one cause. Our study seeks to test this hypothesis by comparing patent assertions against the same biosimilar drugs in the United States, United Kingdom and Canada.