Editors' Summary: This Article is the first of a two-part series that examines the promise and reality of Clean Air Act enforcement by reviewing four central enforcement issues: (1) the development of the "any credible evidence" rule; (2) the evolution of the compliance assurance monitoring proposal; (3) the controversy over the requirement of federal enforceability of limitations on a source's potential to emit pollutants for purposes of determining its status as a "major source" under the Act; and (4) the tension between state-law voluntary disclosure, immunity, and environmental audit privileges and EPA's enforcement policy for state Title V operating permit programs.

This Article briefly reviews some of the new enforcement tools created by Congress through the 1990 Clean Air Act Amendments. It then examines one of the most important of these tools—the "any credible evidence" rule—which is central to the prospect of vigorous citizen enforcement of the Act. It next reviews the issues surrounding development of the "compliance assurance monitoring" rule—a rule that is expected to generate detailed compliance information that regulators and citizens can use for enforcement purposes. The Article concludes that while both rules are consistent with Congress' desire to strengthen clean air enforcement, these rules are likely to cause a fundamental shift in the realities of clean-air enforcement for industry, citizens, and regulators alike.