Different explanations exist as to the reason that Chazal don’t create g’zeirot (protective prohibitions) on top of other g’zeirot (ein gozrin g’zeirah l’g’zeirah). R. Herschel Schachter (Eretz HaTzvi, 6), citing R. Yitzchak Elchanan Spektor (Resp. B’er Yitzchak), relates the explanation based on the fact that Chazal did not enact g’zeirot lightly; they only put one into place in situations of “great need”. Protecting biblical law from violation is such a need; protecting rabbinic law is not (in the perspective of Chazal). Thus, Chazal would not enact a g’zeirah to protect one of their own g’zeirot.

The Minchat Elazar (I, 37) represents a different view, based upon an often quoted comment of the Netivot HaMishpat (C.M. 234) that one who inadvertently (b’shogeg) violates a rabbinic prohibition needs no atonement. This is understood to be consistent with the view held by many acharonim that rabbinic prohibitions are not inherent in the relevant object (issurei cheftza), but rather are injunctions upon the individual (issurei gavra) to respect rabbinic authority. (Other acharonim, such as R. Yosef Engel. Atvan D’Orayta, 10, dispute this understanding.) If so, when there has been no disrespect, as the transgression was unintentional, there is consequently no crime to atone for.

G’zeirot are, for the most part, aimed at avoiding inadvertent transgressions; a willing sinner will carry out his plans regardless of g’zeirot. Thus, it would be unnecessary to make a g’zeirah to protect a rabbinic law, as the inadvertent transgression would be insignificant. If, however, notes the Minchat Elazar, there is a possibility of violating biblical law, even a double g’zeirah may be indicated.