California’s bill would punish doctors for discussing disfavored ideas, making it almost certainly unconstitutional. Some liberal public-health experts say that makes the Constitution the problem. “Vaccine misinformation during the COVID-19 pandemic underscores how reverence for freedom of speech in the US intensifies our vulnerability to public health threats,” Stanford’s Michelle Mello recently wrote in the Journal of the American Medical Association.

Ms. Mello laments “the Supreme Court’s attachment to a particular conception of free speech rights,” which limits the government’s ability to impose speech restrictions. She suggests that state medical boards can “suspend the licenses of physicians whose statements constitute unprofessional conduct,” which could include “misinformation” as they define it.