In this shiur we went through the bottom line regarding when, if at all, one is permitted to rely on the lenient position of the Ittur – permitting amira even on an issur d’orayta. You can see the mekorot at this link – we began with the Tur and went through the relevant passages in the Shulchan Aruch.
The discussion of the Ittur’s lenient position lead to an important distinction regarding two different types of minority opinions. There are occasions when an opinion is not the accepted law, but it can be relied upon in certain circumstances. However, the unique approach of the Or Zarua (that writing in a language other than Ashurit and Greek is not an issur d’orayta on Shabbat) seems to be a shita that has been rejected from the History of Halakha. This is a concept that I call “Halakhik Darwinism.”