The original location, as well as the primary fulfillment, of Bircas Kohanim seems to be in the holy precincts, first in the Mishkan (Tabernacle), and afterwards in the Beis Ha-Mikdash (Temple). In fact, the Torah relates that upon concluding the sacrificial service of the eighth day of the Mishkan's dedication, Aharon blesses the people:
“And Aharon raised up his hands toward the people and blessed them; and he came down from offering the sin-offering and the burnt-offering and the peace-offerings.” (Vayikra 9:22)
Based on this verse, the first mention of the concept in the Torah, the ceremony of Bircas Kohanim is often referred to as Nesias Kappayim, “Raising the Hands.” Indeed, the Rambam, in his Sefer Ha-mitzvos, lists Bircas Kohanim among the positive mitzvos associated with the Beis Ha-mikdash and its service (Mitzvas Aseh 26)
The Mishna (Tamid 7:2) lists three differences between the blessing recited in the Beis haMikdash as opposed to the one recited outside.
ElementInside the Bais haMikdashOutsideBlessingOneThreeName of G-dShem Ha-MeforashPseudonymLift handsAbove their headsShoulder levelThe Gemara (Sotah 38a) arrives at a similar conclusion.
While these sources indicate that the Priestly Blessing is to be recited OUTSIDE the Beis haMikdash as well, it also clearly indicates the uniqueness, if not the primacy, of Bircas Kohanim as it is recited in the Beis haMikdash. In fact, even outside of the Beis haMikdash, the kohanim bless the people immediately after the berakha of "Retzeh," which petitions for the restoration of the Temple service!
If so, one might ask whether, technically, the mitzva of Bircas Kohanim OUTSIDE of the Beis haMikdash is biblical (mi-de'oraita) or rabbinic (mi-derabbanan).
The Yerushalmi (Nazir 7:1), as well as the Rishonim (Rambam, Sefer Ha-mitzvot, Aseh 26; Ramban, Bamidbar 8:2; Sefer Ha-chinukh 378, etc.), and Acharonim (Keren Ora, Sota 38a; Peri Megadim, OC 128:3, etc.), agree that Bircas Kohanim, outside of the Beis haMikdash, and even after its destruction, remains mi-de'oraita.
However, even if the obligation of Bircas Kohanim applies equally outside of the Beis haMikdash, one may still ask: is its nature different? Furthermore, one might also question whether Bircas Kohanim, in general, should be seen as a part of the daily service in the Beis haMikdash; or whether, fundamentally, Bircas Kohanim is a form of tefilla, recited both inside AND outside of the Beis haMikdash.
Interestingly, the Mishna chooses to include the laws of Bircas Kohanim in Tractate Sotah, adjacent to laws of the ceremony of the "Berakhos U-kelalos" (Blessings and Curses) on Mount Gerizim and Mount Eival, and not in Tractate Berakhos, which addresses the laws of prayer and blessings directly.
The Rambam cites Bircas Kohanim, in his Sefer Ha-Mitzvos, among the other mitzvos related to the Beis haMikdash. However, he puts the laws of Bircas Kohanim alongside the laws of prayer, calling the entire unit "Hilkhos Tefilla U-nesias Kappayim," "The Laws of Prayer and Raising the Hands!"
These sources highlight the apparent ambiguity in, or dual nature of, Bircas Kohanim.
There appear to halakhic similarities or differences between Bircas Kohanim in the synagogue and Bircas Kohanim in the Temple service.
We seem to find an apparent contradiction in the Talmud. On the one hand, the gemara in Sotah (38a), deriving that Bircas Kohanim should be recited while standing, cites a baraita:
"In THIS way you shall bless" — STANDING. You say that it means standing, but perhaps that is not so and [the blessing may be pronounced] even sitting! It is stated here, "In this way you shall bless," and elsewhere (Devarim 27:12) it is stated: "These shall stand to bless" (referring to the Mount Gerizim ceremony) — just as here, it is standing; so too in the former passage, it is standing.
Rabbi Natan says: "[This deduction] is unnecessary; behold, it states [regarding the kohanim]: 'To serve Him and to bless in His Name (ibid. 10:8)' — as [the priest] serves standing, so he blesses standing. How do we know that the service [was performed standing]? Because it is written [regarding the kohanim]: 'To stand to serve (ibid. 18:5).'"
This Gemara concludes that just as the kohen must perform all of the other parts of the Temple service while standing, so too he must recite Bircas Kohanim while standing. This apparently supports the position which views Bircas Kohanim as a form of Temple service.
On the other hand, the Gemara elsewhere (Ta'anis 26b-27a) appears to reject this comparison:
Everyone agrees that one who is intoxicated may not perform Bircas Kohanim. How do we know this? Rabbi Yehoshua ben Levi said in the name of Bar Kappara: "Why is the section relating to the kohen taught immediately following the section relating to a nazir (who is prohibited to drink wine)? [To teach that] just as wine is forbidden for a nazir, so too wine is forbidden for a kohen who blesses." If so, then just as grape seeds are forbidden for a nazir [so too a kohen]! Rabbi Yitzchak says: "The verse says 'To serve Him and to bless in His Name' - just as one who serves (i.e., a kohen during the Temple service) may consume grape seeds, so to a kohen who blesses may consume grape seeds. If so, just as one who serves may not have a blemish (mum), so too a kohen who blesses... It is merely an asmakhta (mnemonic), and it is of rabbinic origin.
Seemingly, this Gemara rejects the above comparison, adopted by the other gemara (Sotah 28a), between a kohen who serves in the Beis haMikdash and a kohen who recites Bircas Kohanim!
While the Gemara does not point out this apparent contradiction, the Rishonim debate whether to apply the comparison between Temple service and Bircas Kohanim.
On the one hand, the Rambam (Hilkhos Tefillah 15:3-4) disqualifies one guilty of idolatry or murder, as well as one who has consumed a revi'is of wine, by comparison to the Temple service. On the other hand, Tosafos (Ta'anis 27a) rule that a blemished or apostate kohen may recite Bircas Kohanim, rejecting the comparison between Bircas Kohanim and the Temple service.
The Acharonim also discuss this question. For example, the Taz (128:27) questions why the Shulchan Arukh rules that if a community is already accustomed to the kohen's physical blemish, he may recite Bircas Kohanim. He asks, based upon the sources cited above, why this kohen should not be disqualified due to the comparison between Bircas Kohanim and the Temple service!
He offers what he himself describes as "a novel explanation, as we have not found this question or its answer in any commentary, old or new." He suggests that while we DO derive from the Temple service those disqualifications which the kohen can avoid, e.g., being drunk or being sedentary, those which relate to his physical appearance, which he cannot avoid, do not disqualify him.
Alternatively, the Magen Avraham (128:54) questions whether an arel, one who is uncircumcised, may participate in Bircas Kohanim. He concludes that one who is uncircumcised MAY participate in Bircas Kohanim, despite his apparent disqualification from Temple service. In other words, he rejects the comparison between Bircas Kohanim and the Temple service.
The Peri Megadim (OC 128) explores this issue, and expends great effort defending the position of the Taz.
Is it possible that just as the Mishna lists the TECHNICAL differences between Bircas Kohanim inside and outside the Beis haMikdash, there may be a fundamental distinction as well? Might we suggest that while in the Beis haMikdash, Bircas Kohanim functions as an integral part of the Temple service, Bircas Kohanim outside of the Beis haMikdash is integrated into the mitzva of tefilla?
We noted above that most Rishonim and Acharonim conclude that the mitzva of Bircas Kohanim applies equally inside and outside of the Beis haMikdash. However, one may certainly suggest (see Keren Ora, Sota 38a) that Bircas Kohanim recited outside of the Beis haMikdash, which lacks the proper use of the Shem Ha-Meforash,
