Michael Dreeben, a veteran U.S. Supreme Court advocate with 105 oral arguments under his belt, will join O’Melveny & Myers in January as a partner in its appellate and white-collar practices, the firm announced Tuesday.

The longtime deputy U.S. solicitor general, widely viewed as an unrivaled expert on criminal law, retired in July after a two-year detour assisting special counsel Robert Mueller in the investigation into Russia’s election interference. In August, Dreeben took on a teaching position at Georgetown University Law Center, which he will retain in private practice.