He attended the Pingry School and Newark Academy before entering Princeton University, where he graduated in 1879.

He studied at Columbia Law School, receiving his diploma in 1882, and was admitted to the New Jersey bar that same year.

[1] McCarter and his brother joined the law firm of their father, which had been established in Newton in 1845 and moved to Newark twenty years later.

Governor Franklin Murphy nominated McCarter to take his brother's spot, and he was confirmed as Attorney General on May 5, 1903.

Though he mostly took on corporate clients, he served as the defense attorney for one of New Jersey's most sensational criminal cases, the Hall-Mills Murder trial of 1926.