IANAL, but I think in California as long as you don't use excessive force it's ok, but yeah if you kill the engine at a high speed or if you get unlucky and the

IANAL, but I think in California as long as you don't use excessive force it's ok, but yeah if you kill the engine at a high speed or if you get unlucky and the thief gets seriously injured then you will get in trouble if they want to go after you.