He was initially interested in a career in journalism, serving as editor-in-chief of The Johns Hopkins News-Letter,[5] as a sportscaster on the school radio station, and as a summer intern at The Baltimore Sun.

After graduation, Nathan clerked for Simon Sobeloff on the United States Court of Appeals for the Fourth Circuit, whom he cites as one of his greatest mentors.

He spent most of his career (over 30 years) at Arnold & Porter, first as an associate and later as the senior litigating partner and head of its white collar criminal defense practice.

[9] From 1979 to 1981, Nathan served as a deputy assistant attorney general in the United States Department of Justice, where he was deeply involved in the Abscam operation.

One of his most notable actions during this time was to compel Bush administration official Harriet Miers and Joshua Bolten to comply with their subpoenas.

One of his most notable acts as attorney general was to sue Harry Thomas Jr., a sitting member of the Council of the District of Columbia, for corruption securing a judgment and a settlement.

He also inaugurated the Charles Ruff fellows program by which recent law school graduates from the local law schools in the District worked for one year at the Office of the Attorney General, lending their energy and talents to the office while securing excellent experience in a quest for fulltime employment either in public service or the private sector.

[16] Nathan represented the city and initially argued that Zukerberg was not suffering any "meaningful hardship" from pushing back the election.