The world recoiled in horror in 2012 when 20 Connecticut schoolchildren and six adults were killed at Sandy Hook Elementary School by a deranged teenager using a military-style assault rifle to fire 154 rounds in less than five minutes. The weapon was a Bushmaster AR-15 semiautomatic rifle adapted from its original role as a battlefield weapon. The AR-15, which is designed to inflict maximum casualties with rapid bursts, should never have been available for purchase by civilians.

This is the eminently reasonable point that the parents of the 6- and 7-year-old students cut down at the school are now pressing in Connecticut state court. They are attempting to sue the gun manufacturer, Remington; the wholesaler; and a local retailer for recklessness in providing the weapon to the consumer marketplace “with no conceivable use for it other than the mass killing of other human beings.”

The question of whether the lawsuit will be allowed to proceed is at issue because Congress, prodded by the gun lobby, in 2005 foolishly granted the gun industry nearly complete immunity from legal claims and damages from the criminal use of guns.

The Sandy Hook parents argue that their suit should continue because that law, the Protection of Lawful Commerce in Arms Act, allows claims against companies — gun shop dealers, for example — if they knew or should have known that the weapons they sold were likely to risk injury to others. The parents contend that the maker of the Bushmaster is no less culpable because it knowingly marketed a risky war weapon to civilians.