I think the degree at Cambridge is the best, it consists of two years in england, and two in france so it truly is a dual degree hence the name{Double Maitrise}. I'm currently studying European Law{French} at Warwick, and I think its a very good program. Kings, and LSE also do but I'm afraid I don't know a lot about their programs. The best Universities in France for law though are Paris I, and Bordeaux.