In 1940 Hensel moved to Washington, D.C., to serve as the first chief of the United States Department of the Navy's legal division for procurement.

In early 1945, Roosevelt nominated him as Assistant Secretary of the Navy,[4] and Hensel held that office from January 30, 1945, to February 28, 1946.

"[7] in order to stop McCarthy's investigation of allegations into Hensel's private business dealings while in government service, specifically that Hensel, while working in procurement for the U.S. Navy during World War II, improperly aided in the formation of a company to supply private shipping companies.

[9] Hensel swore an affidavit on June 16, 1954, denying McCarthy's charges, sent it to the subcommittee's chairman, Senator Karl Mundt, and made it public.

[6] He joined Simpson Thacher & Bartlett and practiced international law in Washington, D.C. From 1966 to 1977, he was a partner with Coudert Brothers.