The Volokh Conspiracy has the story:
A unanimous 3-judge decision of the District of Columbia Court of Appeals has dismissed a municipal lawsuit brought against firearms manufacturers, District of Columbia v. Beretta et al. The court ruled that the suit was barred by the Protection of Lawful Commerce in Firearms Act, which was passed by Congress in 2005, and which by its terms applies to all pending and future cases.
In the first part of the decision, the court rules that the congressional act applies to lawsuits brought under D.C.'s Strict Liability Act, which imposes absolute liability on manufacturers for certain firearms injuries. The second part of the decision rejects various arguments that it is unconstitutional for a congressional statute to be applied to a lawsuit that has already been filed.