Do we allow the transgression of a minor sin in order to prevent a major one?
The Shulhan Aruch (Orah Haim 254) brings the classic case. If a person puts dough in an oven on Shabbat, the Rabbis let him take it out before it bakes. There is a rabbinical prohibition of taking out bread from an oven on Shabbat, however we say that better he transgress a rabbinical law than a biblical one, of baking on Shabbat.
Hacham Ovadia Yosef in Yabia Omer (Yoreh De’ah, Helek 6 ,Siman 3) brings a couple of cases where this dilemma arises.
A nursing lady who is divorced or widowed is not allowed to get married until the baby is 24 months old. If a nursing lady wants to get married within these 2 years, and we know if we don’t let her she will live a promiscuous lifestyle; do we say, let her get married and push off this rabbinical law, in order to save her from living promiscuously?
A lady who had Halisa (if a man dies without children, the widow is obligated to either marry the deceased’s brother, or perform the ritual of Halisa with him) done to her is not allowed to marry a Kohen. The case arose where such a lady threatened the Rabbis that if they don’t let her marry a Kohen she will convert to Christianity. Do we say she can marry the Kohen in order to stop her from converting?
Biblically, a lady who is Nidda can go to the Mikveh on the 8th day of her impurity. The rabbis decreed that this is not allowed. A lady who says she will only go to the Mikveh on the 8th day, will we waive this rabbinical law in order that she will go to the Mikveh?
A hotel requested kosher supervision on their food. This hotel however, gave customers upon request milk in their coffee after a meat meal. Do we say, give them the rabbinical supervision in order to prevent major Kashrut issues and overlook this disregard of the rabbinical law?
It was prevalent in the Hi"da’s (Rabbi Haim Yosef David Azoulai, 1724-1806) time for people to shave with a razor. The rabbis were trying to solve this issue being that it is a sin from the Torah to shave with a razor. The people said that if the Rabbis allowed them to shave on the Omer, they would not shave with a razor anymore. The Hi"da questioned, do we say let them break this custom of shaving on the Omer in order that they stop transgressing a biblical law?
Regarding this subject, each scenario must be analyzed and judged individually. Much caution and deliberation must be exercised while judging such cases being that the violation of Halacha is involved.