NASCAR drivers have been getting out of their cars on the track during cautions for years, including some who exit in anger to approach other drivers still behind the wheels of moving cars.
"I don't know how you can enforce a rule like that unless you had a robot on the track to grab the person and put them back in the car," Keselowski said during a conference call with reporters Tuesday. "The only way you can enforce it is with a penalty system afterward. Really at that point, it's not effective. It's a difficult rule to try to make work."
The discussion comes after Ward, who had left his wrecked car and was on the track trying to confront Tony Stewart, was struck and killed by Stewart's car during a dirt track race at Canandaigua Motorsports Park on Saturday night.
Stewart is not currently under criminal investigation, but Ontario County Sheriff Philip Povero said on Monday that the investigation remains open. He said there were "no facts that exist that support any criminal behavior or conduct" or "any probable cause of a criminal act."
Keselowski, who himself has run across a track during a caution period, is unsure that NASCAR needs to react with a rule prohibiting drivers from leaving their cars, except in case of fire.
"Whether it's racing or society, I'm not aware of any rule or law that works without the ability to enforce it," Keselowski said.
"I hate to put myself in NASCAR's shoes. I think sometimes we put so many rules in place, it's almost impossible to enforce them all. I don't know what the line is or if there should be a line or an area that needs a rule. Man, I'm glad I don't have to make that decision."