Legal Director





Mateo Caballero is the Legal Director of the American Civil Liberties Union of Hawaiʻi. The legal department engages in impact litigation to challenge the most pressing threats to civil rights and liberties in Hawaiʻi with a strategic focus on decarceration, decriminalization of poverty, and police reform.

Mateo’s notable cases and matters with the ACLU of Hawaiʻi include challenging FDA regulations on abortion pill on behalf of Kauai doctor and health care associations under Administrative Procedure Act and 14th Amendment, filing a Title IX lawsuit on behalf of female student athletes challenging unequal opportunities, benefits, and treatment in their high school athletics program, obtaining a court order allowing hormone therapy treatment for transgender minor in foster care over the parents’ objection, obtaining asylum for Yemeni post-doc student and his family after being denied asylum in the aftermath of President Trump's travel ban, and helping prepare a report on bail practices in Hawai‘i.

Before joining the ACLU of Hawaiʻi, Mateo was in private practice both in Hawaiʻi and Washington, D.C. While his practice centered in general civil litigation and internal investigations, Mateo was involved in significant civil rights and pro bono matters, including the representation of indigent defendants in eviction proceedings, seeking clemency on behalf of a mentally impaired person in death row in Virginia, and representing people in parole hearings.

Born in Colombia and raised in Venezuela, Mateo came to the United States for college, receiving a B.S. in mathematics and philosophy with highest honors from the Washington and Lee University in 2004 and a J.D., cum laude, from Harvard Law School in 2007. He was a law clerk to U.S. Bankruptcy Court Judge Elizabeth Stong.