Carter died from complications of a stroke Tuesday in New York, his son, John W. Carter, told The New York Times.
As a member of the NAACP Legal Defense and Educational Fund Inc., led by Thurgood Marshall, Robert L. Carter argued the segregation of public schools was unconstitutional, resulting in the 1954 Brown vs. Board of Education ruling abolishing state-sanctioned segregation in schools.
His argument led the Supreme Court to overturn the precedent set in 1896 by the Plessy vs. Ferguson ruling upholding a Louisiana law requiring segregation on railroad cars. That ruling was used to justify segregation throughout the South until 1954.
"We have one fundamental contention," Robert L. Carter told the court. "No state has any authority under the equal protection clause of the 14th Amendment to use race as a factor in affording educational opportunities among its citizens."
He wrote in his 2004 book, "A Matter of Law: A Memoir of Struggle in the Cause of Equal Rights," that psychological testimony showing black children suffered as a result of segregation was crucial in persuading the court. He said his activism started when, as a 16-year-old in East Orange, N.J., he stood up to a teacher's threat to have him expelled for using his high school's pool on a day black students were restricted.