The Supreme Court said it has no authority to change an international treaty on child abduction. (Andrew Harrer/BLOOMBERG)

A unanimous Supreme Court ruled Wednesday that it has no authority to change the terms of an international treaty on child abduction to benefit a father who missed a deadline for demanding the return of his child, whose mother took her to another country.

It is the third time in four years that the justices have considered how to interpret articles of what is known formally as the Hague Convention on the Civil Aspects of International Child Abduction. Federal courts are having difficulty reconciling some of the provisions of the agreement with domestic family law.

At issue in this case was where custody hearings should be held to resolve a dispute between Manuel Jose Lozano and Diana Lucia Montoya Alvarez, Colombians who met in London and had a daughter in 2005.

Lozano has described their relationship as good; Alvarez says Lozano was physically and emotionally abusive. In 2008, she left to take their daughter to nursery school and never returned. She stayed at a women’s shelter for months, then moved to France and then finally to live with her sister in New York.

All agree that Lozano diligently looked for his daughter, but it was not until two years later that he discovered she was in New York. He filed a motion to have her returned to Britain.

The Hague Convention says that if a motion is filed within 12 months of the abduction, the child must be returned to the country of origin. But after that, a judge may consider whether a child has become “settled” in his or her new home and whether it would be in the child’s interest to be uprooted again for custody hearings.

Lozano couldn’t file the motion before the 12-month deadline because he didn’t know where his daughter was. He is asking the court to find that the 12-month period does not start until a parent locates the child.

Justice Clarence Thomas wrote for the court that the treaty does not allow the deadline to be extended, as is sometimes the case with domestic statutes.

He noted Lozano’s argument that sticking to the 12-month deadline gives abducting parents an incentive to keep their whereabouts a secret.

But the treaty did not aim at preventing abductions “at any cost,” Thomas wrote. It also was concerned about the well-being of the child, and not uprooting her again, or returning her to a dangerous situation.

Justice Samuel A. Alito Jr. agreed with the decision, but in a concurring opinion joined by Justices Stephen G. Breyer and Sonia Sotomayor, he noted that although deadlines in the treaty are rigid, judges still have discretion in their rulings.

“The fact that, after one year, a child’s need for stability requires a court to take into account the child’s attachment to the new country does not mean that such attachment becomes the only factor worth considering when evaluating a petition for return,” Alito wrote.

The case is Lozano v. Montoya Alvarez.