Eager to participate in World War I, in 1918, Ellis volunteered to serve in the United States Army but was rejected for physical deficiencies.

In 1919, Kirkland and Ellis defended Robert R. McCormick and the Chicago Tribune in a libel suit brought by Henry Ford.

Kirkland and Ellis would win a major battle for freedom of the press in the Supreme Court of the United States with Near v. Minnesota, 283 U.S. 697 (1931).

During the largest antitrust case in history at the time - that involving DuPont - Ellis represented the Du Pont family.

(The government was attempting to force the Du Ponts to dispose of their stock holdings in General Motors and the United States Rubber Company.)