The Restatement (2nd) of Torts states:
(1) An actor is subject to liability to another for assault if
(a) he acts intending to cause a harmful or offensive contact with the person of the other or a third person, or an imminent apprehension of such a contact, and
(b) the other is thereby put in such imminent apprehension
Therefore, Assault has three elements:
- apprehension of a harmful contact, and
Assault is distinguished from battery because there is no requirement of actual contact - just a mental disturbance in the victim. Of course, there must be actual causation - if the act fails to cause such an apprehension, the Plaintiff cannot argue that it could have or would have in a different person.
Mere words do not constitute assault - there must be an accompanying act. Further, there must be the apparent ability to carry out the act: if a reasonable person would not think the actor capable of fulfilling the threatened contact then there is no assault. The courts have been hesitant to apply assault in the context of an "eggshell plaintiff" - one who is uncommonly susceptible to harm (the tort most commonly found in these situations is Intentional Infliction of Emotional Distress).