Victims of the Boston bombings and their family members may end up participating in the immigration reform debate in the same way that parents of the children cruelly murdered in Newtown, Conn., contribute to the ongoing debate about gun violence: As impossible-to-ignore witnesses to the urgency of the issues raised by these terrible massacres.

The Boston bombers are legal immigrants. At least one of them is believed to have left and returned to the country in recent years. Their assimilation was assumed. Everyone they knew testifies to surprise and shock that they had become ruthless killers and Islamist fanatics.