ONE WHO DRANK MAY NOT GIVE BIRKAS KOHANIM [Birkas Kohanim :wine]
(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).)
Ta'anis 26b: All agree that a Shikur (one who is drunk) may not Duchan.
(R. Yehoshua ben Levi): Parshas Nazir is next to Birkas Kohanim, to forbid wine to a Kohen who will Duchan, just like a Nazir.
Question (R. Zeira's father): If so, one who ate Chartzan (grape peels) should be forbidden to Duchan!
(R. Yitzchak): "Lesharso u'Levarech bi'Shmo" - just like Sherus (Avodah) is permitted after one ate Chartzan, also Berachah.
Suggestion: Just like a Ba'al Mum cannot serve, he cannot Duchan!
Rejection: The Hekesh to Nazir shows that he may. These Hekeshim are mid'Rabanan, so we are lenient.
Krisus 13b (Beraisa) Suggestion: "Yayin v'Shechar Al Tesht" - perhaps one is liable for entering the Mikdash after drinking any amount of wine, or wine mi'Gito (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.
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.
Rav Acha came to Rav Ashi (on Yom Tov) to permit a vow. Rav Ashi told him to return tomorrow, for he conducted like Rav, who would not expound on Yom Tov (after drinking) until the next day, lest he be drunk. Even though the Halachah follows R. Elazar, and Rav Ashi drank wine mixed with water, R. Elazar exempts only when he drank only a Revi'is (of diluted wine). Rav Ashi drank more than a Revi'is.
Rambam (Hilchos Tefilah 15:4): One who drank a Revi'is of undiluted wine at once may not Duchan until the wine wears off, for Berachah is equated to Avodah. If one drank a Revi'is in two times (he paused in the middle), or a little water was added, he may Duchan. If one drank more than a Revi'is, even if it was diluted, even if he paused many times in the middle, he may not Duchan until the wine wears off.
Kesef Mishneh: If one drank a Revi'is in two times, or it was diluted, he is exempt for entering the Mikdash. Therefore, he may Duchan, for the Hekesh is a mere Asmachta. It suffices to forbid Birkas Kohanim when one would be liable for entering the Mikdash.
Tosfos (Ta'anis 17a DH v'Yode'a): Wine that one drinks during a meal does not intoxicate. It does not forbid a Kohen to serve in the Mikdash.
Shulchan Aruch (OC 99:2): Walking a Mil (about a kilometer) or any amount of sleep wear off the effect of wine. This is if he drank a Revi'is. If he drank more, sleep inebriates (even more) and walking disturbs him.Riding in a carriage wears off wine.
Beis Yosef (DH u'Mah she'Chosav v'Derech): This is from Eruvin 64a.
Shulchan Aruch (128:38): One who drank a Revi'is of wine at once may not Duchan. If one drank it in two times, or a little water was added, it is permitted.
Beis Yosef (DH Shikur): R. Yerucham says that a Shikur may not Duchan if he is as drunk as Lot, like we say in general. It seems that he holds that the Isur for a Shikur to Duchan is because it is like Tefilah. I disagree. It is because Birkas Kohanim is equated to Avodah, like the Rambam writes! Therefore, even if one drank a Revi'is he may not Duchan. This is the Halachah.
Magen Avraham (55): R. Yerucham is correct. The Gemara learns Birkas Kohanim from Nazir. If so, other intoxicants are permitted. There is no Misah for other intoxicants, so they are permitted regarding Birkas Kohanim, unless he is as drunk as Lot, for then he is exempt from all Mitzvos. It seems that even if he cannot speak in front of the king, he may Duchan. This is unlike Tefilah. I do not understand why the Beis Yosef says that R. Yerucham equates it to Tefilah. It seems that if one drank grape juice he is Pasul (to Duchan), for it is forbidden for a Nazir. Therefore, the Rambam did not mention this.
Kaf ha'Chayim (227): Nishmas Adam (32:2) says that just like grape juice disqualifies, even though it does not intoxicate, the same applies to raisin wine, for we learn from Nazir. Pesach ha'Dvir says those who learn from Nazir would forbid also cooked wine. Eliyahu Rabah says that if one may Duchan after drinking other intoxicants, which obligate lashes for one who does Avodah, all the more so one may Duchan after drinking grape juice, for which there are no lashes for Avodah. According to those who forbid other intoxicants, also grape juice forbids l'Chatchilah.
Mishnah Berurah (141): The Shulchan Aruch discusses wine. Regarding other intoxicants, the Magen Avraham permits even if he cannot speak in front of the king. Tefilah in such a state is an abomination, but Birkas Kohanim is permitted, unless he is as drunk as Lot, for then he is like a lunatic.Many Acharonim disagree and say that if he cannot speak in front of the king, he may not Duchan. If one drank grape juice, the Rema forbids to Duchan, but many Acharonim permit, for it does not intoxicate.
Kaf ha'Chayim (225): Since Acharonim argue about other intoxicants, l'Chatchilah a Kohen may not ascend to Duchan until they wear off; but if he ascended, he does not go down.
Shulchan Aruch (ibid): If one drank more than a Revi'is, even if it was diluted, even if he drank it in many times, he may not Duchan until he the wine wears off.
Beis Yosef (DH u'Mah): The Rambam understands that just like one who drank more than a Revi'is is liable for Avodah even if it was diluted, the same applies if he drank it in many times. Therefore, he may not Duchan.
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 in two times, he may not serve, but he is exempt and the Avodah is Kosher. This is astounding. If so, what is the Rambam's source that for this, we do not equate Berachah to Avodah? One cannot say that the Hekesh is a mere Asmachta. Hekesh is one of the methods for expounding the Torah! There is no hint in the Gemara that this Drashah is only an Asmachta. Tosfos (Sotah 38a Sof DH Harei) says that if one gave Birkas Kohanim sitting, he must bless again, due to the Hekesh to Avodah! If it were only an Asmachta, Tosfos would not tell a Kohen to say Hash-m's name Levatalah! (Note - Tosfos did not explicitly say that he repeats the Berachah 'Asher Kideshanu b'Mitzvosav...' To repeat the verses of Birkas Kohanim is not Shem Hash-m Levatalah.) Therefore, I say that if one drank a Revi'is in two times, he may serve. The Kesef Mishneh (Hilchos Bi'as Mikdash 1:2) 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, even though there is no Chiyuv Misah for them, surely he may not Duchan, since the Torah forbids Avodah, even though it is only a Lav. Since there is no explicit Shi'ur for beer or mead (a drink made from fermented honey) like there is for wine, a Kohen may not drink any amount of intoxicants before Birkas Kohanim, even though the Beis Yosef says that the Hekesh is only for matters for which one is liable regarding Avodah.
Taz (26): Any Kosher who does not Duchan must leave the Beis ha'Keneses at the time, lest people say that he is a Chalal (Pasul Kohen). The Mordechai says so about a Kohen Avel.
Taz (27): We disqualify a Kohen with a Mum on his hands if people will look at it. He should be Pasul due to the Hekesh to Avodah! It seems that "Daber El Aharon v'El Banav" includes Ba'alei Mumim, like Rashi (Parshas Emor) says. It does not include Pesulim that come due to man's actions. "Banav" alludes to what is due to birth. The Hekesh teaches only about what man can fix, e.g. sitting or drinking.
Magen Avraham (54): We say in Ta'anis that the Hekesh is only to be lenient, to permit Chartzan, but not to be stringent. A Ba'al Mum and many others Pasul for Avodah taught in the second Perek of Zevachim are Kosher for Birkas Kohanim. The Hekesh is only for standing. The Rambam says that one who is drunk is Pasul due to the Hekesh of Berachah to Avodah, to teach that just like if he paused while drinking or mixed in any water he is exempt, likewise he may Duchan. Had we learned from Nazir, we would have forbidden one who drank any amount, even if it was diluted.
Kaf ha'Chayim (226): If he is as drunk as Lot, even if he ascended, he goes down. Mateh Yehudah and Eliyahu Rabah say that the Mechaber says so even if he drank a Revi'is. I say that one may rely on the lenient opinions b'Di'eved, to avoid embarrassing him.
Kaf ha'Chayim (228): Some Acharonim forbid even if he drank during his meal. Birkas Kohanim is more stringent than Tefilah. However, Tosfos (Ta'anis 17a) says that this does not forbid even Avodah! All the more so, he may Duchan! We rule like the Pri Megadim said about Tefilah. If one feels the influence of wine, he may not Duchan until the wine wears off.