Mason, a southerner, was a temporary appointment as Attorney General. Polk placed him in office between the terms of two Northern appointees. His only significant ruling during a brief tenure was on the status of the Black Seminoles. Mason ruled for the South:
"My opinion is, that the Military authorities should be instructed to restore the Negroes to the condition in which they were with the Seminoles, prior to the date of Major General Jesup's letter of the 8th of April 1846."
Completely sidestepping Jesup's 1838 proclamation, Mason ruled that the Black Seminoles were property. This meant that their owners
-- or those who successfully claimed to be their owners -- could dispose of them at will.
Sources: U.S. Attorney General 4: 720-29, Giddings Exiles 327-28, Foreman Five 257, Littlefield 122-25, Mulroy 45.
Part 3, Exile: l