In July 2011, NFL running back Rashard Mendenhall sued Hanesbrands Inc. for terminating his million-dollar contract to promote Champion sportswear. Mendenhall's deal was canceled after he sent out controversial tweets on sociopolitical topics, including an attempt to temper celebration after Osama bin Laden was killed.
The lawsuit, the NFL star's lawyers presented at the time, involved the question of whether a "celebrity endorser loses the right to express opinions simply because the company whose products he endorses might disagree with some (but not all) of these opinions."
Source: Hollywood Reporter. Read full article. (link)