Monitoring and enforcement of environmental regulations. Lessons from a natural field experiment in Norway

Relying on a small natural field experiment with random assignment of treatments, I estimate effects of three core elements of most monitoring and enforcement practices: self-reporting, audit frequency and specific deterrence. I find evidence of evasive reporting of violations in self-audits, as more violations are detected in on-site audits than in self-audits. Announcing the increased audit frequency has no effect on compliance, but an audit raises the firm’s subsequent compliance substantially.