WASHINGTON, June 27 - The Supreme Court ruled on Monday that the police did not have a constitutional duty to protect a person from harm, even a woman who had obtained a court-issued protective order against a violent husband making an arrest mandatory for a violation.

The decision, with an opinion by Justice Antonin Scalia and dissents from Justices John Paul Stevens and Ruth Bader Ginsburg, overturned a ruling by a federal appeals court in Colorado. The appeals court had permitted a lawsuit to proceed against a Colorado town, Castle Rock, for the failure of the police to respond to a woman's pleas for help after her estranged husband violated a protective order by kidnapping their three young daughters, whom he eventually killed.

For hours on the night of June 22, 1999, Jessica Gonzales tried to get the Castle Rock police to find and arrest her estranged husband, Simon Gonzales, who was under a court order to stay 100 yards away from the house. He had taken the children, ages 7, 9 and 10, as they played outside, and he later called his wife to tell her that he had the girls at an amusement park in Denver.

Ms. Gonzales conveyed the information to the police, but they failed to act before Mr. Gonzales arrived at the police station hours later, firing a gun, with the bodies of the girls in the back of his truck. The police killed him at the scene.