MBE Fast Fact: Necessity

The defense of necessity in Torts is all about balancing harms, and on the MBE, it's a safe bet to assume it'll show up in a question that requires you to determine if one had the privilege to enter another's land. (Because if one has the privilege, then there is no trespass.)

A person has a privilege to interfere with the real or personal property of another when it is reasonably and apparently necessary to avoid threatened injury from a natural or other force, and when the threatened injury is substantially more serious than the invasion that is undertaken to avert it. That last part is quite important and plays into the balance of harms. In order for necessity to be a valid defense it must be true that the harm you were trying to avoid is substantially greater than the harm you might cause in trying to avoid the other harm.

The two types of necessity are public and private necessity. Public necessity provides for the defense when harm to the public is threatened whereas private necessity allows for the defense when an act is solely to benefit a private individual or property belonging to that individual. An important difference here is that even if one has the privilege of private necessity, the actor must pay for any damages caused by the act resulting from the necessity. So, if X while flying his private airplane is threatened with the possibility of a substantial injury, and to avert that injury, X lands his plane on the property of Y, then, even if X had the privilege to land on Y's property, X may still be liable if landing the plane causes any damage to y’s land.