What is Androlepsy?

Legal Definition
Androlepsy, in ancient Greek law, was a custom in Athens that if a citizen was killed abroad, and the criminal was not delivered for punishment, the victim's relatives were allowed to arrest as many as three citizens of the offending city. They would be held hostage until the actual criminal was handed over, and perhaps tried for murder instead of him. The Greeks called this androlepsia, and the Romans clarigatio. The persons entrusted with the office of seizing the three hostages were usually the trierarchs, and the commanders of warships.

The word is formed of άνήρ, "man", and λαμβάνω, "I take".

Some authors also use androlepsia for reprisals.
-- Wikipedia
Legal Definition
The taking by one nation of the citizens or subjects of another, in order to compel the latter to do justice to the former. Wolff. 1164; Molloy, de Jure lar. 26.
-- Bouviers Law Dictionary
Legal Definition
The taking by one nation of the citizens or subjects of another, in order to compel the latter to do justice to the former. Wolffius, § 1164; Moll, de Jure Mar. 26.
-- Black's Law Dictionary
Legal Definition
Holding aliens as hostages to compel their nation to do justice.
-- Ballentine's Law Dictionary