The legal concept of in pari delicto holds that in a "case of equal or mutual fault [in a financial fraud] the position of the defending party [auditor] is the stronger one." The predicate for this defense is imputation: holding the corporation responsible for the acts of its officers.
The leading case authority is Cenco Inc. v Seidman & Seidman, a 1982 case where the court permitted an auditor to invoke the in pari delicto doctrine to defeat a claim against it for failing to detect fraud by the management of an audit client.
From an ethical perspective, do you think auditors should be able to escape legal liability for failing to uncover fraud under the doctrine.