Beginning in the 1950s, some Conservative rabbis have used the Lieberman clause, named for Talmudic scholar and Jewish Theological Seminary (JTS) professor Saul Lieberman, in the "ketuba", requiring that a get be granted if a civil divorce is ever issued. Most Orthodox rabbis have rejected the Lieberman clause, although leaders of the Conservative movement claim that the original intent was to find a solution that could be used by Orthodox and Conservative rabbis alike, and that leaders of Orthodox Judaism's Rabbinical Council of America, and respected Orthodox rabbis, including Joseph B. Soloveitchik, supposedly recognized the clause as valid. Later, because some civil courts viewed the enforcement of a religious document as a violation of the constitutional principle of the separation of church and state, Conservative rabbis began to require couples to sign a separate letter, stating that the clause had been explained to them as part of pre-marital counseling, and that both parties understood and agreed to its conditions, recognizing that this letter would constitute a separate civil document, enforceable in a civilian court. However, many Conservative rabbis, including some on the movement's own law committee, had growing misgivings about the clause for religious reasons.