The Supreme Court’s 2008 District of Columbia v. Heller decision affirmed that the Second Amendment protects an individual right to arms. Two years later, McDonald v. Chicago made that right enforceable against state and local governments.

The McDonald Court declared that the Second Amendment is not a “second-class right,” to be “singled out for special — and specially unfavorable — treatment.” In 2019, however, Heller is in a precarious situation: There have been numerous victories for gun rights, but many lower courts have in practice nullified the Second Amendment. Later this year, the Supreme Court may hear a case involving egregious …