Police officers usually cannot be forced to pay damages under a federal civil-rights law for killing or injuring someone during a high-speed chase, the Supreme Court ruled Tuesday.

The court ruled unanimously that the parents of a California teenager struck and killed by a deputy's car cannot sue the deputy under a federal civil rights law. The justices said police can be held liable only when their actions would "shock the conscience."The court rejected a more lenient standard urged by the youth's parents, whose lawsuit accused the deputy of violating their son's constitutional rights by engaging in a dangerous pursuit at speeds approaching 100 mph.

"We hold that high-speed chases with no intent to harm suspects physically or to worsen their legal plight do not give rise to liability under the 14th Amendment" and federal civil rights law, Justice David H. Souter wrote for the court.

"A police officer deciding whether to give chase must balance on one hand the need to stop a suspect and show that flight from the law is no way to freedom and, on the other, the high-speed threat to everyone within stopping range," Souter said.

Tuesday's ruling reversed a federal appeals court decision that let the parents of 16-year-old Philip Lewis sue Sacramento County deputy sheriff James E. Smith over their son's death on May 22, 1990.

Lewis was a passenger on a motorcycle that failed to stop when another deputy tried to flag it down. When Smith saw the motorcyclists keep going, he followed in pursuit.

The chase went through several stop signs and forced two other cars and a bicyclist off the road. The pursuit ended when the motorcycle skidded to a halt.

Smith tried to stop his car but hit Lewis, knocking him nearly 70 feet down the road. The youth was pronounced dead at the scene.