Quote of the Day - 98% of all statistics are made up.
The company, Allegheny Ludlum, charged with violating the CWA believed it was in compliance with reporting requirements, but due to a laboratory error, they actually were overreporting zinc concentrations due to the laboratory's contaminated reagent. The USEPA brought an administrative action to levy fines. After imposing some $8 million in fines, the company fought the allegations in a lower court and lost. They appealed, and won, creating this new defense.
The USEPA argued that the CWA imposed a strict liability scheme, and there could therefore be no exceptions. Although the Circuit court disagreed with the government, the court would not endorse the laboratory error defense as an actual affirmative defense to the USEPA's charges, but noted that it was "relevant" to compliance determinations.