[T]he essence of the action of false imprisonment is the compelling of a person to stay at a particular place against his or her will. Accordingly, where a plaintiff has full knowledge and comprehension of the defendant's coercive conduct amounting to total restraint, the action depends upon proof that, were it not for the defendant's conduct, the plaintiff would not have submitted to the restraint. Consequently, it is not sufficient in law that conduct of the defendant has contributed to or influenced the plaintiff's decision to remain unless the conduct has overborne the plaintiff's will. It must be shown that, but for the defendant's conduct, the plaintiff would not have yielded to the total restraint ...
[A]lthough the idea of false imprisonment is sometimes expressed in terms of a restriction on liberty which must be total, that does not mean that a restriction short of lock and key may not be actionable. In each case, it is a question of fact as to whether a restriction is so severe as to be characterised as false imprisonment. For example, if a victim is confined to an island, and the only means of egress is by swimming through dangerous waters to the mainland, there is no reasonable means of egress and the victim's confinement to the island is likely to amount to false imprisonment. If, however, there is reasonable means of egress or escape from detention, the restriction may not be enough. So, if a victim is confined to a room, and there is a reasonable means of egress through a door, the victim is in effect free to leave the room and there is no false imprisonment [41] [42].
[F]alse imprisonment is the complete deprivation of liberty although ... something short of confinement under lock and key may constitute false imprisonment. All that may be required is that the victim be constrained to remain at the will of the wrongdoer. But, a mere partial interference with freedom to travel by one route as opposed to another does not compel a person to remain. He or she is free to leave by the other route [85].