© D.L. Crumbley
Under the rules, CPAs cannot provide a service for an audit client that only someone licensed to practice law can perform.
The concern this rule addresses is that the auditor would be acting as an advocate, which the SEC (partly in reliance on United States v. Arthur Young)
Source: T.J. Purcell, III and D. Lifson, “Tax Service After Saebanes-Oxley,” Journal of Accountancy, November, 2003, p. 37.