The FDA’s just-unveiled Draconian restrictions on vaping products are an example of good PR but bad public-health policy. And regulators know better.

When he headed the FDA, Dr. Frank Young used to admonish his minions that there were times when common sense should modulate established policies and rules. That can be done in federal agencies via “enforcement discretion,” a tool that regulators use to carry out their mandate in light of sometimes ambiguous laws and regulations.