An elderly and sick U.S. citizen has been held hostage for three years by a rabbinical court in Israel. He is being threatened with imprisonment if he tries to leave Israel and return to his home in the U.S., where he needs medical treatment from his long-term doctors. Not only is this elderly man a U.S. citizen, he has absolutely no connection to Israel: He is neither a citizen nor a resident of Israel.

His crime? Having a son, from whom he is estranged and who lives in the U.S., who has refused to give a religious divorce (a get) to his ex-wife who lives in Israel. Although the evidence proves that the hostage father, who is religious, has absolutely no influence over his irreligious son, the rabbinical court, which is not really a court of law by any acceptable standards of justice, is holding the father as a bargaining chip to compel his American son to grant the get. The father is also being sanctioned with an astronomical sum of 5000 shekels per day until his son gives a divorce.

If this sounds like something that could only happen in an Iranian sharia court, it’s just as bad in Israel, where the rabbinical courts claim legal authority to impose their religious rulings on any Jew who sets foot on Israeli soil. In this case, the hostage is not even a party to the legal proceeding between the estranged husband and wife. Since the son is safely in the U.S., and thus beyond the reach of the Israeli rabbinical courts, the only leverage the rabbis have over the irreligious son is to hold his religious father as a hostage.

There can be little doubt that the Israeli rabbinical court is holding this American citizen as a hostage in violation of Israeli law, Jewish law, and basic humanitarian principles applicable to all nations. The Israeli Supreme Court has held that hostage taking is unlawful even when national security interests are at stake. In the well-known case involving Lebanese hostages held as bargaining chips by Israeli authorities, former President Aaron Barak of the Israel Supreme Court ruled that there is absolutely no basis in Israeli law for holding hostages in order to influence the conduct of others. Jewish law, likewise, prohibits punishing innocent fathers for the sins of their sons. And basic humanitarian law looks askance at collective familial responsibility under which a father is held hostage to compel his son to do something he has chosen not to do.

Yet the rabbinical judges, some of whom seem to make up the law as they go along, have chosen to violate all these principles, in a desperate effort to achieve a desirable end — namely, produce a get for a woman who was left an agunah, a term for a woman whose husband has left her. But a desirable end cannot be achieved by unlawful means.

Recently in the U.S., a group of young Jewish men also decided to use unlawful means to extort a get from an unwilling husband. In that case they kidnapped the husband, threatened him physically, and beat him. The U.S. authorities arrested the young men, who claimed in their defense that they were trying to achieve a just result. The court properly rejected that proposed defense, convicted the young men, and sentenced them to prison. The rabbinical court is acting comparably to these young criminals by seeking to extort a get by unlawful means. But what the Israeli rabbinical court did was, in some respects, even worse. The young men went directly after the sinner who refused to give the get. The rabbinical court is using life-endangering physical threats against a sick old man who has absolutely no control over his son’s behavior.

I have agreed to help achieve justice for the hostage father, because he is an American citizen being improperly detained and sanctioned in Israel by the rabbinical court in violation of law. We plan to bring this injustice to the attention of United States authorities, since the hostage is a U.S. citizen, not an Israeli citizen, who is being prevented from exercising his right to return to his own country to obtain the medical care he needs from his long-term doctors. The American authorities may find it difficult to believe their closest ally Israel is allowing this rabbinical court to act in so an unlawful manner against a U.S. citizen. But the facts are there for all to see.

I am assured by the father’s Israeli lawyer Yael Nagar, his rabbinical advocate Rabbi Moshe Mittelman, and by multiple family members that there is no possibility that the father can persuade his son to give the get and that there is no credible evidence to the contrary in the record. Recently, the father was hospitalized in the intensive care unit and put on life support due to a chronic illness. The estranged son is in total disregard to his father's medical and hostage situation. Nothing will be gained by keeping this frail and elderly U.S. citizen from returning to his country. The goal of the rabbinic court is to obtain a get for the aguna, not to punish her former father-in-law. Unless the rabbinical court’s decree is reversed, this old man will almost certainly die away from his home, and his son will continue to refuse the get.

No rabbinical court should have authority over an American citizen who happens to be Jewish. Religion should not have the compulsion of the government to enforce its decrees, especially against noncitizens who are not even parties to the legal proceeding. Religion should rely on moral persuasion, not state-sanctioned physical force. Theodore Herzl hoped that in the Jewish state “We shall keep the priests [Rabbis] within the confines of their temples.” This hope was not realized, but the rabbis must not be given the authority to compel religious observance, especially against one who is not a party and has no power to enforce its religious decree.

I will not rest until this gross injustice of trumped up unproven charges and sanctions to a U.S. citizen are ended and he is allowed to come home.

Alan Dershowitz (@AlanDersh) is a contributor to the Washington Examiner's Beltway Confidential blog. He is the Felix Frankfurter Professor of Law, Emeritus, at Harvard Law School and author of The Case Against Impeaching Trump (Skyhorse Publishing, 2018). This piece was originally published by Israel Today.