This brief essay responds to recent court decisions and scholarly commentary questioning the constitutionality of the Affordable Care Act. Criticism has focused in particular on the provision imposing a $695 penalty on those who fail to purchase qualifying health insurance. I argue that, contrary to the courts and the commentators, this provision is valid as an exercise of Congress\u27 power to lay and collect taxes. Although much has been made of Congress\u27 use of the word penalty rather than tax, the Supreme Court has held since 1866 that Congress can invoke the tax power in litigation without using that term in the challenged statute. I also reject any normative arguments for rejecting that venerable rule as unpersuasive. In any even...