Gregory Gymnasium was named in honor of his efforts to provide an adequate exercise facility for the students and faculty of the university.

"[2] He embraced the progressive rhetoric of the early 20th century by his condemnations of "plutocratic power," "predatory wealth," and "the greed of the party spoilsmen" and participated in Edward M. House's Democratic coalition.

Despite a continuing commitment to progressive reform, Gregory provoked enormous controversy performance as attorney general because of his collaboration with Postmaster General Albert S. Burleson and others in orchestrating a campaign to crush domestic dissent during World War I. Gregory helped frame the Espionage and Sedition Acts, which compromised the constitutional guarantees of freedom of speech and press, and he lobbied for their passage.

He encouraged extralegal surveillance by the American Protective League and directed the federal prosecutions of more than 2000 opponents of the war: "By 1918 the Attorney General was able to declare, 'It is safe to say that never in its history has this country been so thoroughly policed.

His portrait was painted in 1917 by the Swiss-born American artist Adolfo Müller-Ury (1862–1947) and hangs in the Department of Justice in Washington, DC.