The legal question in this appeal is whether, as a matter of law, a police officer is ineligible for ordinary disability benefits as a member of the Police & Firemen's Retirement System (PFRS) if the officer separates from service by irrevocably resigning from employment to resolve pending drug-related disciplinary charges. Recognizing that N.J.S.A. 43:16A-8(2) requires disability retirees to return to duty once their disability has "vanished or has materially diminished," and emphasizing that an irrevocable resignation makes returning to duty impossible and therefore deprives the PFRS Board of Trustees from terminating benefits, this court held that such a member is ineligible.