Gardena police Lt. Steve Prendergast says Irabu was stopped May 17 when officers saw him drifting outside traffic lanes and he nearly collided with a parked car.
Records show the 41-year-old Irabu, who lives in Rancho Palos Verdes, posted $5,000 bail.
Prendergast says prosecutors will decide what specific charge will be filed against Irabu when results of his blood test are received in about a month.
Irabu pitched for the Yankees, Montreal Expos and Texas Rangers from 1997 to 2002.
He returned to Japan and the Kochi Fighting Dogs in 2009 before suffering a knee injury.
An attorney for Irabu could not be located and there is no phone listing for him.