Phyllis, his wife of 67 years, told the Washington Post she could not specify a single cause of the Saturday death. "He was 92 years old, and I think he died of old age."
In October 1973, Cox precipitated what would become known as the "Saturday night massacre." He insisted on obtaining tape recordings of conversations of President Richard Nixon in the Oval Office.
The demand came after five men with links to Nixon's re-election committee had been arrested in the June 1972 break-in at the Watergate headquarters of the Democratic National Committee.
Nixon refused and demanded Cox's firing, but Attorney General Elliot Richardson, who had recruited Cox as the Watergate special prosecutor, refused to fire Cox and resigned, as did his deputy, William Ruckelshaus. The third-ranking officer of the Justice Department, Robert Bork, followed Nixon's order and dismissed Cox.
Before Watergate, Cox served in various government positions, including solicitor general during the Kennedy administration and chief of the Wage Stabilization Board during the Truman administration.
He was a nationally known expert in labor and constitutional law and the author of several books in those fields.
He and his wife had three children.