A police rule meant to prevent officers from shooting at moving vehicles is once again in the spotlight after an off-duty officer killed an unarmed driver over the weekend.

The New York City regulation prohibiting officers from shooting at a moving vehicle unless the driver or occupants are wielding a deadly weapon other than the vehicle itself is one of the strictest in the country.

Now, however, a law enforcement group, 100 Blacks in Law Enforcement Who Care, is saying the weekend’s killing could have been avoided if the police commissioner had put more emphasis on the rule after the death of Sean Bell, an unarmed driver who died in a hail of 50 bullets last fall.

“The police commissioner is sitting on his hands when it comes to enforcing police department policy,” a spokesman for the group, Marq Claxton, said.

The police department said it would not comment on the charge.

In the most recent New York case, an off-duty officer, Raphael Lora, is accused of shooting at a Honduran immigrant, Fermin Arzu who was driving away after crashing into a parked car in front of the officer’s Bronx home.

Relatives of Arzu, who have hired a lawyer from the Reverend Al Sharpton’s organization, the National Action Network, called for Mr. Lora’s immediate arrest yesterday.

Mr. Lora is a former Marine who did not serve in any major conflicts but earned five awards before he was honorably discharged in 1994. The police have not commented on whether he may have violated police guidelines in firing at Arzu.

In both the Bell and Arzu cases, the officers who shot and killed drivers may have believed their victims were armed or reaching for weapons — a potential gray area on which both cases may hinge.

Many other police departments consider vehicles themselves a potentially deadly weapon, allowing police officers to shoot at unarmed drivers as a last resort. Lately, several departments, including Los Angeles and Boston, have moved to adopt the stricter version used in New York City after similar shooting incidents. The International Association of Chiefs of Police also recently adopted a model policy on firing at moving vehicles with language that mirrors New York City’s regulation.

A police shooting expert at the University of South Carolina, Geoffrey Alpert, warned that the stricter policy is no good if not followed.

To address such concerns following to the Bell shooting, the New York City Police Department has commissioned an independent study of its firearms training and procedures, which is due out this summer.