There would be no law against drunk driving, so a cop could not stop a suspected drunk driver to get him off the road prior to killing someone..
http://tigerboard.com/boards/view.php?message=14027414
http://www.ocregister.com/articles/ledezma-726587-street-police.html
Careli Ledezma had just spent the last hour laughing, holding hands and dancing to Mexican folk music with her mother and sisters at a friend’s party.
They were crossing the street to their own apartment when, suddenly, a car struck her mother and two of the girls.
In an instant, they were dead.
“It was terrifying,” said 16-year-old Careli Ledezma, who had watched in disbelief. “It all happened so fast.”
Two Placentia police officers were nearby at about 10:20 p.m. Saturday when they heard the impact of the crash, said Placentia Police Sgt. Michael Busse. They rushed to the 800 block of West La Jolla Street, a block lined with apartments, townhomes and small houses.
There, they found Patricia Ledezma, 34, and her two daughters, Stephanie, 8, and Dayana, 4, lying in the street.
The three could not be saved, Orange Fire Authority Capt. Steve Concialdi said. Firefighters from OCFA were joined by crews from Anaheim and Fullerton.
Police found the driver, identified as Nicolas Stephen Munoz, 27, standing next to his car. Munoz, of Placentia, who was uninjured, was booked on suspicion of murder and driving under the influence with injuries, Busse said.