Editors' Summary: In order to register a pesticide under FIFRA, the registrant must submit data on the pesticide's safety and efficacy to EPA. FIFRA's provisions on EPA's use and disclosure of such data have proved controversial. In particular, the provision allowing EPA to use one manufacturer's data to support the application of another has repeatedly been challenged as an unconstitutional taking of property. In Monsanto Co. v. Acting Administrator, Environmental Protection Agency, the issue has reached the Supreme Court. Messrs. Safir and Reagan analyze the FIFRA taking issue, examining the history of the challenged provision, how various lower courts have dealt with challenges to it, and what routes are open to the Supreme Court. Finally, they consider the potential impact on similar federal registration statutes should the FIFRA provisions be struck down.