Gemara

(Beraisa) Suggestion: Perhaps "Yayin v'Shechar Al Tesht" obligates for entering the Mikdash after drinking any amount of wine, or wine mi'Gito (unfermented grape juice)!

Rejection: "V'Shechar" refers to something that is Meshaker (intoxicates), i.e. a Revi'is of wine pressed at least 40 days ago.

Question: If so, why does it say "Yayin" (which connotes even if it does not intoxicate)?

Answer: This forbids entering the Mikdash after drinking any amount, even mi'Gito.

R. Yehudah says, "Yayin" forbids only wine. "V'Shechar" forbids other intoxicants.

Question: If all intoxicants are forbidden, why does it say "Yayin"?

Answer: One is Chayav Misah (b'Yedei Shamayim) for wine, but not for other intoxicants.

R. Elazar expounds (as if it said) "Yayin Al Tesht; v'Shechar Al Tesht" - do not drink in an intoxicating way;

If he paused while drinking, or added any amount of water, he is exempt.

The first Tana learns a Gezeirah Shavah "Shechar-Shechar" from Nazir (that only wine is forbidden). R. Yehudah does not learn the Gezeirah Shavah. R. Elazar says that Shechar connotes something than intoxicates.

Question: Who is the Tana of the following Beraisa?

(Beraisa): If one ate a date of Ke'ilah, drank honey (cooked with water) or milk and entered the Mikdash and served, he is liable.

Answer: It is like R. Yehudah.

(Rav): The Halachah follows R. Elazar.

(Rav Ashi): The Halachah follows R. Elazar. He exempts one who drank exactly a Revi'is of diluted wine, but not for more than a Revi'is of diluted wine

Zevachim 17b (Beraisa) Question: What is the source that a Kohen who drank wine is Mechalel Avodah?

Answer: "Yayin v'Shechar Al Tesht... u'Lehavdil Bein ha'Kodesh u'Vein ha'Chol" (Avodah done while drunk is Chol (profane)).

Nazir 3b (Mishnah): If one said 'I am a Nazir from grape skins'..., all laws of Nezirus apply to him.

This is unlike R. Shimon;

(Beraisa - R. Shimon): One is a Nazir only if he vows to abstain from all three Isurim;

4a: R. Shimon learns a Gezeirah Shavah "Shechar-Shechar" between Nazir and the Isur to serve in the Mikdash when drunk;

A Nazir may not drink wine, but other drinks are permitted. Also the Isur to serve is after drinking wine, but not after other intoxicating drinks. This is unlike R. Yehudah:

(Beraisa - R. Yehudah): If one ate figs of Ke'ilis or drank honey or milk and entered the Mikdash, he is Chayav Misah.

Bechoros 45b (Mishnah): One who is drunk (may not serve).

Question: One who is drunk is Mechalel Avodah. He should be listed among Pesulim that are Mechalel Avodah!

Answer: The Mishnah discusses someone drunk from things other than wine. It is unlike R. Yehudah:

(Beraisa): If one ate a date of Ke'ilah...

Rishonim

Rambam (Hilchos Bi'as Mikdash 1:1): If a Kosher Kohen drank wine, he may not enter (the Azarah) past the Mizbe'ach. If he entered and served, his Avodah is Pasul and he is Chayav Misah b'Yedei Shamayim. This is if he drank a Revi'is of pure wine at once that is at least 40 days (from when the grapes were pressed). If he drank less than a Revi'is, or he drank a Revi'is and interrupted in the middle, or it was diluted, or it was within 40 days and even if he drank more than a Revi'is, he is exempt and the Avodah is Kosher. If he drank more than a Revi'is, even if it was diluted and he interrupted and drank it bit by bit, he is Chayav Misah and the Avodah is Pasul.

i. Rebuttal (Ra'avad): The Gemara holds that he is not Chayav Misah and the Avodah is not Pasul. He transgresses only a Lav.

Rambam (2): If he was drunk from other intoxicating drinks, he may not enter the Mikdash. If he entered and served while drunk from other intoxicating drinks, even from milk or dates, he is lashed and the Avodah is Kosher. One is liable only for wine at the time of Avodah, and the Avodah is Pasul only if he was drunk from wine.

Teshuvas ha'Rashba (363, brought in Kesef Mishneh): The Gemara says that the Halachah follows R. Elazar. Rashi and the Ra'avad rule like him. Why did the Rambam rule like R. Yehudah? (Really, he rules like R. Elazar.) We cannot say that R. Elazar does not learn the Gezerah Shavah from Nazir. If so, he would expound Shechar for other intoxicants, and not for wine in an intoxicating way. The Gemara discussed all three Tana'im, asked 'who is the Tana of the Beraisa about eating ate a date of Ke'ilah...', and said that it is like R. Yehudah. Surely it is only like him. The Gemara suggested that "Yayin" obligates for any amount, even grape juice. "Shechar" teaches that it is only for a Revi'is, and for 40 day old wine. This is even if he paused and it was diluted. The Gezerah Shavah to Nazir excludes other intoxicants. Since we learn from the Gezerah Shavah, Yayin is extra. It teaches a Lav for wine in a way that does not intoxicate. We cannot say that there is Misah even in this case, for then we would not need Shechar. R. Yehudah expounds Shechar like it connotes, i.e. all intoxicants. He does not learn the Gezeirah Shavah. Shechar is not free to teach about enough to intoxicate. Rather, even if one drank less than a Revi'is, he is liable, and all the more so if he drank a Revi'is, even if he paused or added water. Rabanan would have said so if not for the Gezeirah Shavah. Therefore, he obligates for any amount of all intoxicants, and for any wine, even grape juice. Wine was taught because one is Chayav Misah only for wine. Other intoxicants are forbidden only with a Lav. R. Elazar holds like Rabanan, that Shechar teaches enough to inebriate. He goes further, and says that one must drink it in an intoxicating way, i.e. without pausing or adding water, if he drank only a Revi'is. R. Elazar forbids all intoxicants, like R. Yehudah. If not, he should have expounded "Yayin Al Tesht Shechar" (in an intoxicating way). Rather, he expounds "Yayin Al Tesht Shechar Al Tesht" (to forbid all intoxicants). Also, the Gemara asked what the first Tana and R. Yehudah learn from "Yayin", but it did not ask about R. Elazar. This is because he holds like the Tana before him (R. Yehudah, that it teaches that Misah is only for wine). He argues with R. Yehudah only regarding what he mentioned, that Shechar teaches that the Isur is drinking in a way that intoxicates. The Beraisa of eating a Ke'ilis date is only like R. Yehudah, because the first Tana exempts others intoxicants, and R. Elazar obligates only for an amount that intoxicants. The Tana did not give a Shi'ur. Since the Halachah follows R. Elazar, there is Misah and a Lav only for a Revi'is of wine after 40 days, without water added and drank without pausing. There is a Lav for other intoxicants only if he drank enough to intoxicate. In Nazir, we say that R. Shimon permits other intoxicants, unlike R. Yehudah. The Gemara is not a peddler! (It did not need to elaborate to say that he is unlike also R. Elazar.) It means that he is unlike R. Yehudah and those who hold like him (regarding other intoxicants). It mentioned R. Yehudah, for he explicitly said so. If you say that R. Elazar agrees, R. Shimon is also unlike R. Elazar. The Rambam needed to explain like this, so the Halachah will follow the Stam Mishnah in Nazir, which is like R. Yehudah. Rav rules like R. Elazar, but regarding other intoxicants they agree. Also, perhaps the Rambam exempts for less than a Revi'is before it is not called drinking, and the Torah said "Al Tesht." R. Yehudah holds that the Shi'ur for wine and other intoxicating liquids is a Revi'is; R. Elazar holds that the Shi'ur for other intoxicants is enough to intoxicate. This is why the Rambam wrote 'if he was drunk from other intoxicating drinks...'

Ri Korkus (on Halachah 1): The Rambam rules like R. Yehudah, for in Shevu'os (23a) the Gemara retracted due to the Beraisa that is like R. Yehudah, and the Mishnah is Nazir is like him. Rav rules like R. Elazar only regarding what he explicitly said (that one must drink in a way that intoxicates).

Gilyon R. Akiva Eiger (in Frankel Rambam): Zevach ha'Shelamim asks that in Bechoros, we say that a Shikur (one who is drunk) is Mechalel Avodah. The Rambam learned from there. Even though the Mishnah is unlike R. Yehudah, it disqualifies someone drunk from other intoxicants. However, if so why is the Beraisa only like R. Yehudah? Also, surely he is Mechalel Avodah due to the verse "Yayin v'Shechar... u'Vein ha'Chol." If so, also Rabanan should say that one who drank grape juice is Mechalel Avodah, for they learn from the verse! This requires great investigation.

Kesef Mishneh: In Halachah 1, the Rambam rules like the first Tana! Perhaps he is merely stringent to be concerned for his opinion.

Poskim

Beis Yosef (128 DH u'Mah): The Rambam understands that just like if one drank more than a Revi'is of wine he is liable for Avodah even if it was diluted, the same applies if he drank it in many times. Therefore, he may not Duchan.

Taz (128:27): If a Kohen has a Mum and people in the city are used to this, the Shulchan Aruch permits him to Duchan, for people will not stare at him. He should be Pasul, for Tosfos (Sotah 38a DH Harei) equates Birkas Kohanim to Avodah! This is why one who drank may not Duchan! It seems that they are equated only for what depends on man's actions, e.g. sitting or drinking. "Banav" is Machshir all Kohanim for Birkas Kohanim, even Ba'alei Mumim, which depends on birth and not on one's actions.

Bach (23): The Tur says that a Shikur may not Duchan. I.e. all agree about this. The Tur connotes that if he drank but is not Shikur, he may Duchan. The Rambam forbids due to the Hekesh of Birkas Kohanim to Avodah. Anyone who is liable for entering the Mikdash is forbidden mid'Rabanan to Duchan. Anyone who is exempt for entering the Mikdash may Duchan, for the Hekesh is a mere Asmachta.

Taz (35): The Kesef Mishneh wrote (and the Beis Yosef connotes) that if one drank a Revi'is but paused, it is forbidden to serve, but he is exempt and the Avodah is Kosher. This is astounding! I say that he may serve. The Kesef Mishneh says so in the name of the Rashba (363). Since the Halachah follows R. Elazar, there is no Misah or even a Lav even for wine unless he drank a Revi'is without pausing. The Rambam agrees. Therefore, he may Duchan. If he drank other intoxicants, the Torah forbids Avodah through a Lav.