CITES BY TOPIC:  force
Black's Law Dictionary, Sixth Edition, p. 644

Force.  Power, violence, compulsion, or constraint exercised upon or against a person or thing.  Landry v. Daley, D.C.Ill., 280 F.Supp. 938, 954.  Power dynamically considered, that is, in motion or in action; constraining power, compulsion; strength directed to an end.  Commonly the word occurs in such connections as to show that unlawful or wrongful action is meant; e.g. forcible entry.

Power statically considered; that is at rest, or latent, but capable of being called into activity upon occasion for its exercise.  Efficacy; legal validity.  This is the meaning when we say that a statute or a contract is "in force."

In old English law, a technical term applied to a species of accessary before the fact. 

See also Constructive force; Excessive force; Intervening force; Reasonable force.

Deadly force.  Force which the actor uses with the purpose of causing or which he knows to create a substantial risk of causing death or serious bodily harm.  Purposely firing a firearm in the direction of another person or at a vehicle in which another person is believed to be constitutes deadly force.  A threat to cause death or serious bodily harm, by the production of a weapon or otherwise, so long as the actor's purpose is limited to creating an apprehension that he will use deadly force if necessary, does no constitute deadly force.  Model Penal Code, 3.11.

Unlawful force.  Force, including confinement, which is employed without the consent of the person against whom it is directed and the employment which constitutes an offense or actionable tort or would constitute such offense or tort except for a defense (such as the absence of intent, negligence, or mental capacity; duress; youth; or diplomatic status) not amounting to a privilege to use the force.  Assent constitutes consent, within the meaning of this Section, whether or not it otherwise is legally effective, except assent to the infliction of death or serious bodily harm.  Model Penal Code, 3.11(1).  See also Battery.

[Black's Law Dictionary, Sixth Edition, p. 644 ]