In one of its most significant disciplinary proceeding to date, the Public Company Accounting Oversight Board has taken down another Big Four engagement partner and may still be working on a case against the audit firm as well.

The PCAOB slapped Deloitte & Touche Audit Partner Christopher Anderson with a one-year suspension from public company audit work, a $25,000 fine, and a one-year restriction on his audit abilities when his suspension expires for his role in the audit of 2003 financial statements for Navistar Financial Corp. The disciplinary order does not make any findings against the audit firm.

In December 2007, the PCAOB suspended engagement partner James Fazio and fined Deloitte & Touche $1 million in relation to its 2003 audit work for Ligand Pharmaceuticals.

The PCAOB says Anderson gave Navistar a clean audit opinion even after discovering shortly before the filing of the company’s 10-K that Navistar overstated assets, revenues, and earnings as a result of $19.7 million in errors. The board’s disciplinary proceeding says Anderson accepted a materiality threshold that he believed to be inflated, accepted the company’s adjustments to offset the overstatements, and authorized the clean opinion before the company completed a reconciliation of the affected accounts.

Claudius Modesti, PCAOB director of enforcement and investigations, could not comment on why the order focused solely on Anderson and not Deloitte as well. “We do not comment on considerations involved in whether to charge firms or persons other than named respondents,” Modesti told Compliance Week. “The Board’s order only finds violations relating to Mr. Anderson.”

Lewis Ferguson, a partner with Gibson Dunn and former counsel to the PCAOB, said the case likely is “highly fact specific,” though he’s not familiar with the details. “The firm tends to be the subject of disciplinary action when there is a failure of oversight or supervision,” he said. “Where a particular partner simply makes an error but the firm was not negligent, only the partner may get named in the proceeding.”

Deloitte representative Deborah Harrington said Anderson remains with Deloitte “with responsibilities consistent with the settlement.” The disciplinary action suspends him “from being associated with a registered public accounting firm,” which specifically is Deloitte & Touche LLP, the firm that is registered with the PCAOB.

The PCAOB has finalized fewer than two dozen disciplinary actions since its first finding in mid-2005. Deloitte is the only Big Four firm to be fined directly, although Susan Birkert of KPMG and Stephen J. Nardi and Ann Marie Fitzpatrick of tier-two firm BDO Seidman were named in 2007 cases.