INDIANAPOLIS (AP) — Indiana’s attorney general says the state’s school districts are free to use extended stop arms to prevent other vehicles from passing school buses.

Curtis Hill says in an official opinion that no federal or state laws prohibit the use of extended stop arms on school buses.

Such opinions don’t have the force of law but are generally respected by courts.

The (Northwest Indiana) Times reports that Hill’s opinion says a state board that sets safety standards for Indiana’s school buses can authorize the use of extra-long stop arms that extend into oncoming traffic.

Extended stop arms are already in use in other states.

Three siblings were struck and killed last October in northern Indiana by a pickup truck while boarding a bus that had stopped and lowered its stop arm.