John Doar was awarded the Presidential Medal of Freedom in 2012
Mr Doar dealt with some of the most prominent civil rights cases of the 1960s.
In 2012, President Obama awarded him the Presidential Medal
of Freedom, calling him "one of the bravest American lawyers of his or
any era".
US media report that he died at his home in Manhattan from heart failure.
Mr Doar played a key role in protecting the rights of black Americans who faced obstacles at the voting booth and in academia.
He escorted James Meredith, the first black student to attend
the University of Mississippi, on to campus despite violent riots
against racial integration which ended in two deaths.
Mr Doar was also the lead prosecutor at a trial arising from
the deaths of three civil rights workers who were shot dead in 1964.
In a statement on Tuesday, Attorney General Eric Holder, called Mr Doar a "giant in the history of the rights movement''.
Mr Doar also played a lead role in the investigation of the
Watergate scandal in the early 1970s which ultimately led to the
downfall of President Richard Nixon.