The gemara[1] states that the congregation should not answer amen before the kohanim have completed each beracha.[2] Is this halacha referring to waiting until all the kohanim have completed the berachot, or is a majority enough?
To answer this question, we must examine parallel contexts of waiting for a group of people to complete a recitation. The gemara cites Rav Chisda as saying that although one who makes the beracha over the bread at the start of a meal should not cut the loaf until those present complete answering amen to his beracha, he need not wait for a minority who unnecessarily stretch out their amen recitation.[3] Similarly, the Shulchan Aruch[4] rules that during chazarat hashatz, the chazan does not need to wait for a minority of the tzibbur who take an unnecessarily long time to answer amen to his berachot before moving on to the next one. The Mishna Berura[5] writes that this rule is generally true about a series of berachot, except in the case of berachot that each member of the group has an obligation to hear. In that case, we need to wait for the last one to finish saying amen before going on, so that he will also hear the beginning of the next beracha.
Birkat Kohanim is a case in which the kohanim must wait for the entire congregation to finish answering amen, because everyone present needs to hear the kohanim’s full berachot.[6] However, in our case, it is a kohen who is not finishing with the others, and it does not seem that there is a concern from the kohen’s perspective if the tzibbur, and certainly a segment of the tzibbur, did not hear and respond to his entire beracha.[7]
Is there a problem from the congregation’s perspective if their amen was premature with regard to the beracha of some of the kohanim? To answer this, we need to understand why the congregation must not answer amen to Birkat Kohanim too early.
The B’er Sheva[8] writes that this is a simple application of a rule regarding all berachot. The gemara[9] refers to an improper amen called an amen chatufa, which some maintain refers to answering before the beracha is completed.[10] However, it is difficult to imagine that this problem would apply after most of the kohanim have finished the beracha, as the amen relates to the beracha of the majority, who have indeed finished, and it is thus not fundamentally too early.
The Halachot Ketanot,[11] in the context of Kaddish, discusses answering reciters who finish at different times. He writes that if they finish within toch k’dei dibbur (approximately 1.5 seconds) of each other, one can choose to answer either after the earlier or the later ones; if they are separated by more than that amount of time, one should answer both separately. The Birchot Horai[12] posits that the same is true for an unevenly finished Birkat Kohanim. However, he also cites Rav S.Z. Auerbach, without a specific citation or explanation, as instructing to wait until the later person is finished.
Should it make a difference that here there is a clear majority and the individual kohen who finishes late is an outlier? We have seen that we follow the majority regarding the end of the response of amen in the contexts of HaMotzi and chazarat hashatz. However, that is apparently because of the assumption that the majority, not the minority, is doing things correctly; if the majority is fast and the minority answers amen at a normal pace, one should wait for the minority.[13] In fact, the main problem with an overly long amen is that stretching out that word distorts it.[14] Regarding our case, if the kohen who is slower is going at a fine pace and is not distorting Birkat Kohanim by being slower, there is reason to presume that it would be better to wait for the last kohen.
The kohanim should ideally recite Birkat Kohanim in unison,[15] although human beings cannot be expected to be exact. Thus, it is not ideal for one kohen to stretch out words significantly longer than his friends. The lack of conformity could arguably make the slower kohen’s recitation considered inappropriate and therefore make it preferable to follow the majority. However, such a determination, especially with the potential for hard feelings it could cause, cannot be made from a distance. It is also not appropriate for an individual congregant to “take a stand” by answering amen at a different time than others in a publicly discernable manner. Therefore, we would recommend to let those who are authorized handle matters and follow what others are doing about the timing of answering amen. Only if different people are answering amen at different times in any event would we recommend that you decide for yourself what to do by applying the nuances presented in our answer to your case.