This rule states that if a lawyer is admitted to practice law "before the highest court of any other state, territory of the United States, Puerto Rico, or the District of Columbia" but not in New Jersey, the lawyer may participate in arbitration, mediation or another form of complementary dispute resolution in New Jersey if both the client and the dispute are from a jurisdiction where the lawyer is admitted to practice.
New Jersey Rules of Professional Conduct 5.5 - Lawyers Not Admitted to the Bar of this State and the Lawful Practice of Law
New Jersey Judiciary. Sep. 1, 2018https://www.njcourts.gov/attorneys/assets/rules/rpc.pdf