Law enforcement in the modern regulatory state is largely a joint enterprise. In areas such as securities, antitrust, civil rights, and environmental law, enforcement responsibilities are allocated between public and private actors. Patent law, on the other hand, is enforced almost exclusively through private lawsuits. Considering patent law’s constitutionally-mandated public purpose — “to promote the Progress of Science and useful Arts” — this privatization of patent enforcement is troubling.In recent years, there has been some movement away from this purely private enforcement regime for patent law. The Department of Justice and Federal Trade Commission, for example, have involved themselves in certain patent matters that implicate antitrust law. While heading in the right direction, these regulators alone cannot adequately enforce patent law due to their limited jurisdiction, resources, and expertise. This Article thus proposes a more robust public enforcement mechanism for patent law. It argues that Congress should arm the U.S. Patent and Trademark Office (PTO), the agency responsible for reviewing patents ex ante, with broad powers to police patent validity ex post. The PTO is best situated to lead this effort because of the agency’s expertise, institutional resources, and enhanced powers under the America Invents Act. Moreover, charging the PTO with the responsibility for policing patents should serve to dispel allegations of agency capture and institutional bias toward patent owners.