Hora'at sha’ah®(a decision for the hour, that is an emergency enactment) and ha-sha-ah tzerikhah le-khakh(the extraordinary needs of the hour). The Rabbis established the right to enact temporary legislation to protect the health and faith of the Jewish people even if it meant contradicting a commandment from the Torah . In these emergency situations the Rabbis frequently evoked the phrase from Psalm 119:126: ef la-asot(it is time for the Lord to word, they have made void Your law).*?
The exceptions to Rabbah’s rejection of the Rabbinic authority to declare kum va-aseh, seem to be reserved for emergency situations. The exceptions were, in theory, only(lefi sha’ah) temporary measures that did not establish precedent, but practically many“emergency” decrees established by the rabbis during times of crisis became permanent. For example, the prohibition against memorizing the“written Torah ” or writing the“oral Torah .” The Talmudic sages understood this law to be de-oraita, based on a law from the Torah . The scriptural citation was Exodus 34:27:44“And the Lord said to Moses :‘Write(ketav-lekha ethadevarim ha-eileh) down these commandments, for in accordance with these commandments(ki al pi hadevarim) 1 make a covenant with you and Israel .”
This verse was interpreted to mean that teachings that were handed down to Moses in writing(i.e., the Torah ) must not be transmitted orally.*® Likewise, teachings that were given orally (ie., Mishnayot and Beraitot) must not be written down.*® But the Mishnah was written down! In writing it down, did not the Rabbis violate a prohibition from the Torah ? However, as Rashi and the Rambam explained, the Mishnah was written down in violation of the Torah only because of the terrible crisis the Jew ish people faced after the destruction of the Second Temple.” The sages cited the emergency authority inferred from Psalm 119:126:“Et la-asot”(When it is time to act for the Lord, you may even nullify your Torah !). This“emergency decree” has now been in effect one thousand nine hundred years.
Ultimately, Joseph Karo , the great codifier of Jewish law, understood that the Talmudic debate between Rabbah and Hisdah was won by Hisdah(Yevamot 90b). The Rabbis had the Authority to permit that which the Torah prohibits.