Maz served as the President of Trill in 2376. That year, Trill was rocked by violence and social unrest when rejected host-candidate Verad Kalon unleashed a virus designed to kill all Trill symbionts and start a civil war in a misguided attempt to "free" Trill from an imagined symbiont dictatorship.
President Maz authorized USS Enterprise-E captain Jean-Luc Picard and Starfleet to take whatever steps were necessary to apprehend Verad and keep the peace. After the crisis was averted, President Maz asked Picard and USS Defiant commander Elias Vaughn and their crews to keep secret the things that they discovered about Trill symbiosis and the percentage of candidate suitability. Picard and Vaughn agreed, but Picard warned Maz that keeping these kinds of secrets from the general populace would cause larger problems in the future. (ST - Divided We Fall comics: "All Fall Down", "United We Stand")
Picard was proved right later that year when it was revealed that the bluegills were an offshoot of the Trill symbionts; this revelation, combined with pre-existing social unrest over the unofficial and unacknowledged caste system that had developed between joined and unjoined Trills, resulted in a terrorist attack upon much of the planet wherein many joined symbionts were killed, including most of the Trill government. President Maz acted to preserve the symbiont population by imposing a moratorium on future joinings, and even utilized an experimental drug to give up her own symbiont, Maz. The unjoined Lirisse Durghan continued to serve as President of Trill. (DS9 - Worlds of DS9 novel: Trill: Unjoined)