It’s hard to think of any clients that would garner more sympathy than the group Josh Koskoff and Alinor Sterling of Koskoff, Koskoff & Bieder represent. The nine families they represent all lost loved ones in the 2012 shooting at Sandy Hook Elementary School.

But it’s also hard to think of a defendant more difficult to hold liable than their litigation adversary, the maker of the semi-automatic rifle used in the shooting. Gunmakers enjoy broad immunity under the Protection of Lawful Commerce in Arms Act, a federal law passed by Congress in 2005.