A passenger sitting in the back seat of my car, which I had just parked in the street to drop him off, opened his door into the street without looking into the path of an oncoming car. The door was knocked off and much damage was done to both cars. He claims I should have warned him, since I have a rear-view mirror and should have seen the oncoming car. I say I never told him to open the door and expected him to look first. Is my passenger obligated to pay the damages?