This book examines Congress’s power to perform that translation—in the words of the Fourteenth Amendment, to “enforce, by appropriate legislation,” the rights that amendment guarantees us. It focuses on the Fourteenth Amendment for a reason: that provision is an absolutely central text if we want to understand what our “constitutional rights” are. One clause of that amendment—the Due Process Clause—is the source of nearly all the substantive constitutional protections we enjoy against deprivations by state governments. Another—the Equal Protection Clause—provides an across-the- board guarantee that state action not unfairly discriminate. The Constitution provides other sources for other rights. But these two are foundational. Just as important as these rights themselves is Americans’ ability to vindicate them. If a state violates a constitutional right, the victim can usually sue. But it is often difficult for a plaintiff to prevail. Sometimes he has a difficult time amassing the proof the Supreme Court has deemed necessary to make out his claim. In some cases this may be because the claim is so enmeshed in a complex bureaucratic or social system that it is difficult for the plaintiff to cut through the haze and identify the single bad actor holding the smoking gun that makes it easier for a court to find a constitutional violation.