Although judicial review is used to police constitutional boundaries, the practice raises serious democratic concerns because unelected judges can overrule the decisions of political majorities. Using an agency model we show that judicial review has a heretofore unacknowledged democracy-enhancing effect. By constraining the policy choices made by elected representatives, judicial review increases the importance of office benefits as compared to policy benefits, making it more likely that politicians behave in the voters' best interests. Politicians do so across policy issues, including those that courts cannot review, leading to a spillover effect. These effects do not depend on the preferences of the court, nor on the courts' decisions being observed by the voters. The overall impact judicial review has on democracy is ambiguous, however, because this democracy-enhancing effect comes at the expense of turning some policies over to the courts. We suggest that this ambiguity can be resolved in favor of democracy by tailoring the courts' jurisdiction or standards of review.