I think that Rav Nahman was not in the category of the excommunication of the Gra however I do think the excommunication was valid.
The reason is something I saw in a commentary of the Rambam Mishna LaMeleh in the beginning of laws of vows [Nedarim] where he brings the Beit Yoseph who brings the Tashbaz that a herem has a category of both a vow and an oath. There the ML himself disagrees and says it only has the category of a vow. Still the point is it is valid.
That is just like one can forbid the use of a loaf of bread on another by saying this loaf of bread is a korban [sanctified for the altar] to you"--so a herem excommunication also has that same kind of validity.
The reason this is relevant to me even though others ignore this issue is that I am horrified by how the Dark Side has taken over the religious world in Israel. I wish that the Gra and Rav Shach would have been listened to.
The reason is something I saw in a commentary of the Rambam Mishna LaMeleh in the beginning of laws of vows [Nedarim] where he brings the Beit Yoseph who brings the Tashbaz that a herem has a category of both a vow and an oath. There the ML himself disagrees and says it only has the category of a vow. Still the point is it is valid.
That is just like one can forbid the use of a loaf of bread on another by saying this loaf of bread is a korban [sanctified for the altar] to you"--so a herem excommunication also has that same kind of validity.
The reason this is relevant to me even though others ignore this issue is that I am horrified by how the Dark Side has taken over the religious world in Israel. I wish that the Gra and Rav Shach would have been listened to.