First Amendment law is structurally unstable because it does not adequately distinguish true and false speech. Free speech law, therefore, is “unpredictable,” meaning that speakers cannot accurately predict whether their contemplated speech will suffer sanction. Unpredictable law causes the Rule of Law’s collapse. This Article demonstrates that an effective first step in improving First Amendment law would be to create well-defined liability for false speech. We conclude that, in particular, scientific speech—a form of speech readily determined to be true or false— must face additional scrutiny. Anticipating serious objections to formalized false-speech liability, we then show that these objections, interestingly, apply with equal force to any form of legal liability. The implication of this fact is that rejection of this Article’s modifications to First Amendment law requires deep reconsideration about how we should administer most legal liability, not only First Amendment law.