Abstract: Proportionality, accepted as a general principle of constitutional law by many countries, requires that government intrusions on freedoms be justified, that greater intrusions have stronger justifications, and that punishments reflect the relative severity of the offense. Proportionality as a doctrine developed by courts, as in Canada, has provided a stable methodological framework, promoting structured, transparent decisions even about closely contested constitutional values. Other benefits of proportionality include its potential to bring constitutional law closer to constitutional justice, to provide a common discourse about rights for all branches of government, and to help identify the kinds of failures in democratic process warranting heightened judicial scrutiny. Earlier U.S. debates over “balancing” were not informed by recent comparative experience with structured proportionality doctrine and its benefits. Many areas of U.S. constitutional law include some elements of what is elsewhere called proportionality analysis. I argue here for greater use of proportionality principles and doctrine; I also argue that proportionality review is not the answer to all constitutional rights questions. Free speech can benefit from categorical presumptions, but in their application and design proportionality may be relevant. The Fourth Amendment, which secures a “right” against “unreasonable searches and seizures,” is replete with categorical rules protecting police conduct from judicial review; more case-by-case analysis of the “unreasonableness” or disproportionality of police conduct would better protect rights and the rule of law. “Disparate impact” equality claims might be better addressed through more proportionate review standards; Eighth Amendment review of prison sentences would benefit from more use of proportionality principles. Recognizing proportionality’s advantages, and limits, would better enable U.S. constitutional law to at once protect rights and facilitate effective democratic self-governance.