A number of bills have been introduced in recent years to put a price on carbon via a federal carbon tax. These proposals generally proceed from the implicit assumption that the federal government in general, and the U.S. Environmental Protection Agency (EPA) in particular, does not already have such authority. That is incorrect. Under a federal statute that has been on the books since 1952, EPA could impose a carbon “tax” any time an administration in power is willing to do so. That is because a charge for using the public’s air to dispose of carbon dioxide and other wastes is technically not a tax, but rather a “user fee.” The confusion stems from a 1990 legal opinion written by the present author when he was EPA General Counsel, which ironically was intended to increase EPA’s use of tradable permits and other economic incentives to regulate pollution. It is time to set the record straight that EPA does have existing authority to impose a reasonable user fee on releases of carbon dioxide and other greenhouse gases, as well as other pollutants, any time that it has the political will to do so.