Conor Medsystems Incorporated v. Angiotech Pharmaceuticals Incorporated and others, 9 July 2008, Case No.  UKHL 49, with thanks to Marc Döring and Rowan Freeland, Simmons & Simmons
The decision clarifies the approach towards identifying the "inventive concept" in a patent claim and represents a move away from "obvious to try" as a test for obviousness. Although, contrary to expectations, the judgments do not review the law of obviousness as a whole, the decision still represents "a significant development in UK patent law", as Lord Neuberger described it in his concurring judgment.
Read the extended summary (provided by Rowan Freeland) here.
Read the decision of the House of Lords (in English) here.