In 1975 he left the firm to serve as general counsel to the Board of Governors of the Federal Reserve System, returning in 1978.

In that capacity he oversaw the development of policy and legislation in the areas of financial institutions, debt management, and capital markets.

After serving as Comptroller of the Currency, 1998–2004, Hawke returned to private practice with the well-connected Washington, D.C. law firm of Arnold & Porter.

During his term as Comptroller, Hawke has stressed the importance of the safety and soundness of national banks through such supervisory initiatives as Project Canary (an "early warning" system) and the "Supervision in the Future", which makes extensive use of technology.

He has introduced management and budget reforms in the internal operations of the Office of the Comptroller of the Currency as well as programs designed to increase workplace diversity.