When does a minority halachic opinion come into play?
In Klalei Haposkim (the tenets for halachic rule-makers) there is a discussion of how minority opinions may be included as a snif (lit., branch, i.e., an extra leg to stand on) to support a psak (halachic ruling) l’heter (leniently). Although mainstream halachah follows certain rules of authority, precedence and majority, at times there are extenuating circumstances that call for a rav moreh hora’ah (a practicing Rabbi) to use more obscure sources to render a psak.
First and foremost the paskening rav is required to have the halachic background and must be a bar hachi (possess the capabilities) to be machria (use discernment) to balance the differing opinions to arrive at a psak; ein l’dayan elah mah she’einav ra’os (a judge must rule by his own perception of the facts).
The acceptable variety of opinions used to render a psak are those of the Shulchan Aruch, the Rema (the primary commentary on the Shulchan Aruch) and the Nosei Keilim (lit.arms-bearer the later commentaries that appear in the printed Shulchan Aruch). However, in the case of a psak that deals with matters d’rabbanan (Rabbinic [versus Biblical] law) or, according to some opinions, a trei d’rabbanan (two Rabbinic laws coincide), and if it is a sha’as hadechak (time of pressing circumstances), there is room to rule according to less popular minority opinions.
At times, a posek reaches a decision by combining all the particular, extenuating circumstances of a situation. In such cases, this halachic decision cannot be used to resolve similar issues where not every one of those factors are present to allow for leniency; an individual psak for out-of-the-norm situations must always be sought.
At times, certain circumstances call for extra stringency and take minority opinions that are particularly machmir (stringent) into account. When it comes to matters of divorce, halachah states that a husband cannot be forced to provide a get. There are different levels of force discussed among poskim, where some include less pronounced forms of psychological or monetary pressure. We are strict with regard to a get and include these minority opinions, on account of the terrible possible fallout—due to the restrictions on eishes ish (a married woman [who forms an extra-marital relationship])—should the get not be administered to the highest standard.