The Hawaii Supreme Court declared Monday that parents who can’t afford a lawyer have a state constitutional right to a court-appointed attorney when the state seeks to terminate parental rights over their children.

In the unanimous decision, Associate Justice Simeon Acoba wrote that the failure of a Big Island Family Court judge to appoint a lawyer for a woman nearly 19 months after the state requested temporary foster custody over her son was an "abuse of discretion."

The justices went on to say that parents have a right to a lawyer under the state Constitution’s due process clause.

From now on, judges must appoint lawyers for indigent parents once the Department of Human Services asks for foster custody over a child, the high court said in the 43-page opinion.

The case involved confidential Big Island Family Court custody hearings over the son, identified only as T.M.

The ruling overturns a decision to terminate parental rights of a Kona mom who was 15 when she gave birth in 2009. Six months after the boy was born, the mother went to a domestic violence shelter because of a reported incident between her and the boy’s father.

Still a minor herself, the mother and her baby went into temporary foster care. Last year, Family Court determined the mother, who battled drug abuse and mental health issues, couldn’t care for her son, according to an appeals court ruling.

Her rights were violated because Family Court didn’t appoint a lawyer to represent her until the boy had been in foster care for nearly two years, her Maui attorney, Benjamin Lowenthal, argued at a hearing before the high court last month.

"The failure to immediately appoint counsel for petitioner even after it became apparent that (Department of Human Services) would seek to terminate petitioner’s parental rights left petitioner without the necessary assistance to prepare for the March 2, 2012, termination hearing," the Supreme Court opinion says. "Petitioner was without legal guidance and did not have an advocate to represent her in negotiations with DHS."

The American Civil Liberties Union of Hawaii and other public service law groups filed a friend-of-the-court brief in the case, saying they want a uniform Hawaii policy guaranteeing legal counsel for all indigent parents who face losing custody of children, regardless of their age, instead of on a case-by-case basis.

Courts in 43 states and the District of Columbia automatically provide court-appointed attorneys in abuse and neglect cases, according to the ACLU.

"We direct that upon the filing date of this opinion, trial courts must appoint counsel for indigent parents upon the granting of a petition for DHS for temporary foster custody of their children," the Supreme Court’s opinion says.

The high court noted that the "right to counsel" is essential to fairness in the criminal court system, and an attorney is also necessary for a "fair procedure" in parental termination proceedings.

The ruling vacates the mother’s termination of parental rights and sends the case back to Family Court for a new hearing.

A spokeswoman for the state attorney general’s office said a statement on the decision was being prepared.