Coercion and Duress
Free choice is voluntary action, the very opposite of the compulsory. What is called, coercion occurs when individuals are compelled by force to do something that they would not do voluntarily.
The individual who surrenders his wallet to a thug who holds a revolver to his head does so under compulsion and involuntarily. He is being coerced. Police, who enforce the law against criminals' exercise coercive force.
If all individuals obeyed the law voluntarily because they acknowledged its authority and its justice, there would be no need for coercive force. Because they do not, coercive force must be used to enforce law in a population that includes individuals who do not acknowledge its authority and justice
What about those acts which no one would do voluntarily, but, which, nevertheless, are not done to avoid the threat of coercive force. Are they done voluntarily or involuntarily?
In his Nicomachean Ethics, Book III, Chapter I, Aristotle considers the action of the captain of a ship who throws his cargo overboard in order to save his ship in a storm at sea. Is he acting voluntarily or involuntarily? Clearly, it is not involuntarily. The captain is not compelled to jettison his cargo under the circumstances, but under those circumstances, he thinks it preferable to jettison the cargo rather than lose his ship.
The word "duress" is used for such actions that partake of both the voluntary and the involuntary. Another word that might be used for such actions is "nonvoluntary." It applies to actions that partake of both the voluntary and the involuntary. The captain could have chosen otherwise under the circumstances. His choice, being free, is voluntary.
All of us, who act under duress, act voluntarily and by free choice. We are not compelled or coerced, but we also do something that no one would regard as desirable.