This article studies the effects of warnings, an enforcement instrument which is often used by environmental inspection agencies. Due to regulatory errors, measured emissions are uncertain and some firms are unjustly penalized. Warnings can then be used as a means to reduce the consequences of...

Classical theory states that the optimal fine equals the damage caused by the crime divided by the probability of detection. But does such an optimal fine exist? We focus on emissions from production, and, even if we assume that the damage function is perfectly known, we still show that the...