Complex sentence: He worked in private practice before serving in the Office of Legal Counsel and on the leadership team of the National Security Division, first as senior counsel to the Assistant Attorney General and then as Deputy Assistant Attorney General for the Office of Law & Policy.
Split into simpler sentences: He worked in private practice before serving in the Office of Legal Counsel. Demers was on the leadership team of the National Security Division, first as senior counsel to the Assistant Attorney General and then as Deputy Assistant Attorney General for the Office of Law & Policy.