Is a divorce that was issued under duress and threat of imprisonment valid, even though the one who pronounced the divorce had no intention of divorcing?

If you are overwhelmingly certain that you will be unjustly imprisoned if you do not divorce your wife—and there is no Shar'i reason to compel you to divorce her—then your divorce does not take effect. For the divorce of one who is coerced does not take effect, and coercion occurs through threats or overwhelming certainty of harm. However, if the coercion is rightful, then the divorce is valid.