Correspondence, memoranda, writings, speeches, research notes, testimonies, newspaper clippings, and other papers reflecting Brant's interest in civil rights and liberties, conservation, and constitutional questions. Documents his newspaper career primarily as editor of The St. Louis star and times (1930-1938), his playwriting (1923-1930), his historical studies of James Madison and the United States Constitution and Bill of Rights, his work as speechwriter for President Franklin D. Roosevelt and as conservation consultant for U.S. secretary of the interior Harold L. Ickes (1938-1940), and the economic and foreign policy of the Roosevelt administration.

Includes Brant's testimony before congressional committees on conservation, Supreme Court reorganization, constitutionality of anti-poll tax legislation, revision of Senate filibuster rules, and suffrage for the citizens of Washington, D.C.; correspondence with fellow members of the American Civil Liberties Union and with individuals prominent in the legal profession; correspondence concerning National Audubon Society activities; and papers from his work on the Emergency Conservation Committee which led to the establishment of Olympic Peninsula, Olympic National Park, Washington (State).

Correspondents include James Abourezk, Dean Acheson, Clarke R. Ansley, Roger Nash Baldwin, Charles Austin Beard, Francis L. Berkeley, Francis Biddle, Hugo LaFayette Black, Bruce Bliven, William J. Brennan, Edmond Nathaniel Cahn, Benjamin N. Cardozo, Emanuel Celler, David Laurance Chambers, Henry Steele Commager, Thomas G. Corcoran, James Couzens, Irving Dilliard, Paul Howard Douglas, William O. Douglas, Don Edwards, Marshall Field, Felix Frankfurter, Mark O. Hatfield, William Temple Hornaday, Hubert H. Humphrey, Harold L. Ickes, Jacob K. Javits, Edward C. Mabie, Dumas Malone, Walter F. Mondale, Priestly Morrison, Grace Morse, Wayne L. Morse, George W. Norris, Ezra Pound, Elzey Roberts, Franklin D. Roosevelt, Wiley Rutledge, Carl Sandburg, Arthur Meier Schlesinger, Willard Shelton, Adlai E. Stevenson, Harlan Fiske Stone, Charles H. Townes, Harry S. Truman, Oswald Garrison Villard, Henry Agard Wallace, Earl Warren, James Russell Wiggins, Aubrey Willis Williams, and C. Vann Woodward.