He remained at the firm until 1966, taking his only leave of absence to become Solicitor General of the United States after President Truman’s December 1, 1952 appointment.

[3] His short Solicitor General service (from December 1952–March 1953) was during the transitional period between the presidencies of Harry S. Truman and Dwight D. Eisenhower.

Cummings only appeared before the Supreme Court in matters concerning alleged violations of the civil rights of convicts in a Florida prison camp and a question concerning the constitutionality of the emergency strike section of the Taft-Hartley Act.

Cummings was nominated by President Lyndon B. Johnson on July 11, 1966, to the United States Court of Appeals for the Seventh Circuit, to a new seat authorized by 80 Stat.

In Sprogis v. United Airlines (1971), Cummings ruled that United Airlines's requirement that female employees be unmarried but allowing male employees to be married constitutes sex discrimination and violates Title VII of the Civil Rights Act.