Deuteronomy:17:11 – According to the Torah that they will teach you, according to the judgment that they will say to you, do it; don’t deviate from the word that they say [neither] right nor left.

Gemora: Jerusalem Talmud: Horayot: Chapter 1: Halacha 1: I might think that even if they say right is left or left is right, you should listen to them anyway. No. Since it says “right nor left” it means, if they tell you right is right and left is left, you should not deviate from them

Sifri: Even if it appears in your eyes that they are telling you right is left or left is right, you should listen to them anyway.

DBS Note: The Jerusalem Gemora and the Sifri appear to contradict each other. Also, note that the Rashi on this posuk is often quoted to support blind obedience to the rabbis. Rashi omits the words “appears in your eyes”.

Torah Temimah Colloquial Translation:
The Gemora needs to comment here because it should have said: Don’t deviate right nor left from the word that they tell you. [The modifier in the sentence is basically a misplaced modifier.] From the fact that is relates right nor left to the WORD that they tell you, we see that the teachers are actually saying “go right” or “go left”.

Also, we have quoted the text in the Sifri according to the emandations of the Vilna Gaon and used the words “appears in your eyes”. However, the meaning is still the same. In other words, even if your opinion is the opposite of the rabbis, you should do it anyway. This is because, as is well known, in many topics there are a variety of thoughts and opinions. As it says in Gemora Berakot 58a – anyone who sees a large multitude of Jews should say the blessing, “Blessed are You, G-d, who knows all secrets”. This is because of the multitude of opinions that occur and no individual mind is like any other. As we also see about any given halacha that there are often opposite opinions. These say “impure” and these say “pure”. These say “forbidden” and these say “permitted”. To such an extent that even something that appears easy in your eyes and that the true view is yours just as clearly as your know your right from your left, never-the-less you should still listen to the rabbis.  

It is clear from this that only under these conditions should you listen to the rabbis when they tell you to go right even though IN YOUR EYES the correct answer is to go left. But if, in truth, they tell you that right is left and left is right one should not listen to them. For example, if they tell you that forbidden fat is permitted or that sexual immorality is permitted certainly it is forbidden to listen to them. This is shown explicitly in the Jerusalem Talmud section quoted above.

The Ramban in his commentary says the following, “Even if you think in your heart that they are mistaken and the thing appears obvious in your eyes like right and left, you should do as the rabbis command. You should NOT say ‘how can I eat this forbidden fat or how can I kill this innocent person?’ Rather you should say that this is what the rabbi who is the commander has commanded and it is required of me to listen to him even if he is in error.” [end quote of the Ramban]

 These words of the Ramban seem to imply that even if the rabbis were to say something completely forbidden in the Torah, it is still required to listen to them. However, the words of the Jerusalem Talmud quoted above explicitly show exactly the opposite. Furthermore, such a view would be totally illogical.

The truth is that we do find in Gemora Rosh haShana 25(a) a comment on the posuk “these are the holidays that you should announce”. The Gemora states that by emphasizing the word “you” we see that even if the rabbis intentionally announce the wrong date for the holiday, the date that they announced is still binding. This, apparently, supports the position of the Ramban. However, I have already proved in my commentary on Parshat Emor that the text in the Gemora that states the word “intentionally” is a scribal error. Rather the word should be written “coerced”. That reading is also the reading of the Rambam and the Torat Cohanim.

So, one needs to be forced to explain the words of the Ramban as I originally wrote in the first paragraph above.  It can’t mean that the rabbi explicitly commands to eat forbidden fat.

DBS Note: The Torah Temimah is saying that the Ramban could not have meant what he wrote literally.