The official view of Orthodox Judaism. There was the revelation of Torah to the Jewish people at Sinai through Moshe Rabbeinu. Torah is no longer in Heaven. Additional elements came from Prophets and the Talmudic Sages (Chazal). This is all filtered to us by Rishonim and Achronim. In other words halacha is a process that took many people many years to develop. Along the way there have been collections such as the Rif, Rosh Tur, and Shulchan Aruch. Basically Halacha is validated by widespread acceptance of the extensive analysis of these sources by contemporary poskim. The above should not be seen as a chidush.
A person who issues rulings based primarily on his personal beliefs or social norms without relying heavily on this Mesorah will generally be ignored or denounced. This has changed in recent years.
When I was a young yeshiva bachor, Rabbi Friefeld once said to me. "People think the Chazon Ish is strange but he liked me." Later the rulings of the Chazon Ish were viewed as chumrahs. Now they are not only main stream - but are considered the only valid view. All this in spite of the fact that Chazon Ish often ignores Mesorah and the widely accepted views of predecessor. He also did not like debating his views with others. His success seems to be the result of having talmidim who are very influential.
My point is that halacha also is dependent on successful PR
Rav Heinemam told me that his rebbe Rav Aharon used to carry a Mishna Berura with him to give greater authority to the Mishna Berura which was not so important prior to WWII.
Similarly Rav Diskin, son in law of Rav Yaakov Kaminetsky told me that Rav Hutner had once said to him "Your shver will have to give a din v'cheshbon for making Rav Moshe the gadol.
The father of a friend of mine was a Rav in California. His aguna cases all went to Rav Moshe. After Rav Moshe was niftar he had a new case but similar to previous cases that he took to Rav Eliyashiv. The response he got was different, "While Rav Moshe was big enough to rely on for his heter but I disagree with him." Rabbi Riskin also claimed he was poskening like Rav Moshe but he wasn't accepted because he is not a gadol.
In recent years there has been cultivated the idea of a gadol whose rulings transcend Mesorah.
Times seem to be changing. I recently asked two of my grandchildren who are very successful members of the yeshiva world. If a beis din of three rabbis from Lakewood or Bnei Brak disagreed with the gadol hador concerning something like vaccination - who do you listen to? Both responded if it is a field that they are familiar then it is three against one.
So on the one hand Chazon Ish is becoming the final authority because he is a gadol but at the same time the concept of gadol seems to be disappearing.
