Charles has appeared in hundreds of appellate matters resulting in more than 120 published Court of Appeals decisions, and has overseen the filing of dozens of amicus briefs at the Supreme Court and the Courts of Appeals. He was counsel of record in Ali v. Achim, 552 U.S. 1085 (2007), and was on the counsel teams in Chaidez v. United States, 568 U.S. 342 (2013) and Department of State v. Munoz, 144 S.Ct. 1812 (2024). NIJC commonly litigates in collaboration with pro bono law firms, in which case Charles appears as co-counsel in the case and provides technical and legal support. He is also the longtime update editor for the U.S. Citizenship and Naturalization Handbook.