He has served as the main attorney for Jerome H. Lemelson, the named inventor on 741 US patents, and the self-proclaimed inventor of bar code scanning. Although Lemelson died on October 1, 1997, Hosier continued to litigate to enforce Lemelson's patents on behalf of Lemelson's heirs, including the Lemelson Medical, Educational and Research Foundation (Lemelson Foundation). "The American Lawyer" reported his income for 2003 at $150 million. Lemelson was a noted philanthropist; Hosier was once known as a boastful and lavish spender, but Hosier has set up a Hosier family foundation that makes many charitable contributions, such as being a major sponsor of the Aspen Institute.