It's someone else's fault!

Consider the following scenario: You are minding your own business crossing the street on foot when a car approaches and starts honking at you to get out of the way. In anger, you hit the front bumper of his car causing the air bag to mistakenly deploy (Here's the video this idea comes from: it doesn't look like it is staged but I could be wrong -- it is pretty funny either way).

So here's the question: who is liable for replacing the air bag (air bags cost about $1000 to replace in the U.S.): the driver, the pedestrian or the car manufacturer? The case for the car manufacturer paying to replace could be made on the argument that the air bag malfunctioned and deployed when it should not have. Air bags are supposed to deploy at impacts of at least 30 mph when they can reduce injury, not in response to a harmless tap or fender-bender.

On the other hand, the pedestrian has no right to damage the car-owner's property, even given the driver's rude behavior. An air bag deploying in response to a mild impact is unexpected, but hitting the front bumper was the so-called "proximate cause" of the air bag deploying. Under a strict liability rule, the pedestrian would be liable since the idea here is that you are liable for any damage intended or not arising out of actions you have no right to engage in. Under a negligence standard, it is less clear. One would have to show the pedestrian could have or should have anticipated damage arising out of her actions.

Finally, we could argue that the driver should be liable for replacing his own air bag. This is not necessarily because he deserved to have his car damaged but rather because owning a car and driving it around inherently has risks. Auto-parts are sometimes covered by warranty but once the warranty expires, you are more or less on your own. Auto-parts have to meet certain standards to prevent manufacturers from selling junk but there is no such thing as a perfect product.

The point is that there is no clear answer to this although my inclination would be to impose liability on the manufacturer. Different legal rules result in different outcomes and so in order to evaluate each of these different systems, we have to trace outcomes under a wide variety of scenarios.