The critical factor in the defense of is that the person would not have committed the crime but for the actions of the government, in other words that the person was *otherwise unwilling*. That is to say, if the actions of the government were the critical factor which converted an otherwise uninterested person into a criminal, then it will be entrapment. But if the government merely provides the opportunity for a person to act on their own criminal intentions, then it is not entrapment.

A good example is the use of bait cars by some urban police departments, which will park an ordinary looking car by the side of the street and keep it under surveillance. When a person hot-wires the car and tries to drive off, they cut the ignition by remote control and move in. Courts have ruled this procedure is not entrapment. Since the bait car was parked in an ordinary way, such that it did not stand out from other cars, it is clear that any person who tried to steal it was already intent on stealing a car, and that notion was not planted in their minds by anything the police department had done.

On the other hand, if the police department had left the car with the windows open, the doors unlocked, and the keys hanging out of the driver's-side door with a sign that said "be back tomorrow", a situation would be created whereby the notion of stealing the car might be implanted into the mind of a person who otherwise might never have stolen a car. Such a case would be entrapment.