The following shows that the commonly accepted view of rabbinic authority is based on the Sifre which is not the authoritative view since it is rejected by the Bavli & Yerushalmi and is not mentioned by Rambam and Shulchan Aruch.
Ramban (Devarim 17:11): Left and Right. Rashi explains that even if the Sanhedrin tell you that right is left or left is right – [you must obey them]. Meaning that even if you are certain that the Sanhedrin has erred and it is as obvious to you as the difference between your right and left – you still must comply with their understanding of the Torah. In other words you can’t argue, “How can I eat that which is prohibited by the Torah or how can I execute this person when I know he has not transgressed?” Rather your attitude must be, “The absolute obedience to the rulings of the Sanhedrin is what G d has commanded me and I must observe the mitzvos exactly as the Sanhedrin (which is in G d’s presence in the Temple) says. The Torah was given to me according to their understanding – even if they err.” This is what happened when R’ Yehoshau had a dispute with the Sanhedrin as to what day was Yom Kippur. R’ Gamliel the head of the Sanhedrin ordered R’ Yehoshua to appear before him on the day that he thought was Yom Kippur (Rosh HaShanna 25a). the necessity for this mitzva is very great. That is because the Torah was given to us in writing and it is known that people don’t think identically in all matters. Therefore it would be natural for disputes over what the Torah means to continually multiply and it would end up that there would be many Torahs instead of one. That is why this verse tells you that one must obey the Sanhedrin which convenes in G d’s presence in the Temple – in everything they say concerning the understanding of the Torah. There is no difference in the requrement to obey whether this Torah understanding is part of the Tradition which goes back what G d told Moshe or what their understanding of the meaning or intent of a Torah verse. This requirement to accept their Torah understanding is because the Torah was in fact given to us according to their understanding. Therefore they must be obeyed even if their view contrasts with your understanding as left contrasts with right and surely if you agree with their understanding. That is because G d’s spirit is on those who serve in His Temple and He does not desert His pious ones. G d always protects them from error and mistake. The Sifri (Shoftim 154) says that you must obey them even if appears that they have reversed right with left and left with right.
Yad HaMelech (Hilchos Maamrim 1:2): …It is clear that according to the understanding of Rashi and the Mizrachi the intent of the Sifre [that one must listen to the rabbis even when it apparently involves Torah prohibitions] is against the view of the Babylonian Talmud and also against the Yerushalmi. Furthermore since the Rambam omits mention of this Sifre therefore we have only the halachic view that is explicit in the Bavli and Yerushalmi. Thus all halachic rulings which appear to contradict the words of the Torah e.g., eating prohibited fats or killing an innocent man – irrespective as to the authority of the rabbi giving the ruling they are not to be accepted. It is stated explicitly in the Yerushalmi and also the Bavli that if someone errs in this matter and thinks it is an obligation to listen to these rabbis to eat fat prohibited by the Torah because he thinks it is a mitzva to always obey the rabbis – this individual is obligated to bring a sacrifice as he would be for eating any Torah prohibited food in error.
*** Even Ramban might hold Sifre only applies if Sanhedrin rejects your view ***
Rav Ovadia Yosef (Yabiah Omer Y.D. 6:7.2): … The Yerushalmi (Horious 1:1) states, that you might think even if they tell you that “right” is “left” and that “left” is “right” that they must be obeyed. Therefore the Torah says that you should only obey them if they say that “right” is “right” and “left” is “left”. But this is the opposite of the Sifre [that you must obey them even if they tell you that “right” is “left” and “left” is “right”…. However according to the explanation of the Ramban (Sefer HaMitzvos Shoreh I) and those who support him [Ran Sanhedrin 87a] there is a reconcilation. According to the Ramban as long as the dissenting view has not been directly presented to the Sanhedrin [or Rabbinic authority] then he must refuse to eat that which the Sanhedrin insists is kosher. [If he eats food that he regards as unkosher because he is relying on the Sanhedrin he must bring a korbon] However once he has directly discussed the issue with the Sanhedrin and they have rejected his view [despite his best efforts] then the halacha becomes that he must obey them [even if he is still convinced he is right.]
Riva (Devarim 17:11): Don’t deviate from what they tell you left or right – Rashi explains,“You must obey them even if they tell you right is left and left is right and surely if they tell you right is right and left is left.” This is an astounding statement. Are we really required to listen to a rabbi who tells you that something that is impure is pure or that something which is prohibited really permitted?! The answer is that this command does not concern Torah obligations but rather Rabbinic decrees. Thus “the right that is really left” is referring to decrees such as not doing the Torah mitzva of blowing shofar because of the concern of profaning Shabbos. The meaning of “the left that is really right” is referring to decrees such as prohibiting marriage to someone who is permitted by the Torah.
