Long recognized in Louisville for his fraud investigations, Cardwell participated in numerous special studies, including those relating to the relief administration in Kentucky during the Hoover presidency, and the City of Louisville and the County of Jefferson for tax purposes.

A contributor to professional journals, he was also a member of the American Institute of Accountants, Kentucky and California Society of Certified Public Accountants, and the American Accounting Association.

Cardwell, the originator of the split-control technique and numerous other audit innovations, has often been called the "father of fraud auditing." His deep conceptualization and detailed exposition of the basic logic and language of auditing for fraud places him among the leading auditing theorists of the past century.