Born in Harlem, New York, he was the son of Leonard James and Evangeline Alicia Paterson.
His father was born on the island of Carriacou in the Grenadines and arrived in the United States via New York City aboard the S.S. Vestris on May 16, 1917.
His mother was born in Kingston, Jamaica, and arrived in the United States on September 9, 1919, aboard the S.S. Vestnorge in Philadelphia with a final destination of New York City.
After receiving his law degree, Paterson became involved in Democratic politics in Harlem during the 1950s and 1960s.
In 1965, Paterson was elected to the New York State Senate, representing the Upper West Side of New York City and Harlem.