The Talmud (Pesachim 91a) makes reference to a “jail [run by] the Jews”. The role imprisonment plays within the halakhic system is a subject of some debate. Rashi interprets the above references as being one of two possible scenarios: a) compelling one to end an inappropriate marriage; b) preventing someone who has struck another from escaping before the consequences of the incident have been determined. As R. Moshe Tzuriel (Otzerot HaTorah, I, pp. 568-9) emphasizes, Rashi is not considering the possibility of prison as a punishment, but only as a temporary measure serving an immediate purpose, which is consistent as well with the Torah’s references to a “mishmar” (see Vayikra 24:12, Bamidbar 15:34). R. Tzuriel dismisses the possibility that a source for Jewish imprisonment as punishment can be found in the book of Ezra (7:21). There, the King Artaxerxes command the assistance of the people in ascending to the land of Israel, and says that all who do not cooperate should be punished in various ways, including “l’esurin”, which seems to be a reference to imprisonment. R. Tzuriel notes two refutations to this source: a) the initiative was from the Persian King, not from Ezra; b) the reference may actually be not to imprisonment but to holding someone in one place in order to receive corporal punishment, as indicated by Rashi (Moed Katan 16a). While the Rambam (Hil. Sanhedrin 24:9) does explicitly identify “imprisonment in a jail”, R. Tzuriel points out that the context of his words is extraordinary, extrajudicial measures (beit din makkin v’onshin sh’lo min ha-din) which are by definition limited and uncharacteristic. The author of the Responsa Tzitz Eliezer, R. Eliezer Yehudah Waldenberg, in an article printed in the journal T’chukah (pp. 28-40) considers the viability of imprisonment within a Jewish judicial system. He notes that the Talmud (Sanhedrin 81b) talks of placing certain offenders who cannot be dealt with by the penalties described in the Torah into a “kipah”. In this confinement, measures were taken to indirectly cause the death of the criminal. However, one of the instances mentioned there does not include that detail. This omission continues in the codification of the Rambam. R. Waldenberg understands this, together with other sources, to mean that there is basis for imprisonment as punishment in and of itself, not only as a method to facilitate other types of punishment. This is also the position of R. Yehoshua Menachem Ehrenberg (Resp. D’var Yehoshua, III, Even HaEzer, 31).