On the morning of January 7, 2015, Cherif and Said Kouachi, two brothers deeply offended by satirical drawings of the Muslim prophet Mohammad published in the French weekly newspaper Charlie Hebdo, exacted their own punishment for perceived blasphemy. They forced their way into a staff meeting in the newspaper’s offices and massacred 12 people. The phenomenon of killing or threatening to kill those who insult you or your way of life has come to be known as the assassin’s veto.

Where should the law come down on this? Should it defend free expression at all costs no matter how inflammatory or who is offended? Or should it permit the state’s coercive power to silence those who trade in insult or invective? This conflict poses a fundamental question: how much expression must a free society tolerate?

European nations have often restricted “extreme speech” while the United States has protected speech short of immediate incitement to violence. Yet Supreme Court Justice Stephen Breyer has urged his fellow jurists to learn from the laws of other nations. Should the United States sustain its broad protections for speech or find a better, more European balance between freedom and other values?