Eli Lilly (NYSE: LLY) just lost a patent fight for its lung cancer drug Alimta to generic drug maker Actavis (NYSE: ACT). This UK court decision would cut the blockbuster drug's patent short by 6 years to 2015, not only in the United Kingdom, but also France, Spain, and Italy. 

At $2.7 billion in 2013 sales the importance of Alimta is already looms large, but when taking into account patent expiration for key franchises Cymbalta and Humalog, it becomes critical that Eli Lilly fight off generic threats in its appeal. 

In this episode of The Motley Fool's health-care show Market Checkup, analysts David Williamson and Michael Douglass discuss the court decision in detail, why Alimta is so important to Eli Lilly, and why investors need to watch the courts closely.