Is there any halachic problem for a kosher meat restaurant to be opened throughout the nine days? And would it affect the hashgacha? Thank you
The general custom is that kashrus authorities do not enforce the closure of meat restaurants in the Nine Days. It is better to close the establishment, but if somebody keeps his restaurant open, we do not object.
The opening of restaurants raises a delicate question of lifnei iver:
Although the prohibition of meat in the nine days is “only” by the force of a custom, Rishonim already address the prohibition with severity, and the concept of lifnei iver will apply to it.
On the other hand, people can of course obtain meat elsewhere, so that the case might be a case of “chad ivra nahara” — the person doing the prohibited action does not require the restaurant to do it — and based on this idea, some are lenient with regard to the question of meat restaurants in the Nine Days (see Yecheveh Daas 3:38).
Yet, some write that in Israel, because other restaurants are also of Jewish ownership, the availability of meat does not change the status of lifnei iver (this depends on a dispute between Rashi and Tosafos, Kiddushin 56a).
It is further noteworthy that according to Tosafos, the idea of mesaye’a, aiding a sinful act, does not apply to rabbinic prohibitions.
In addition, there is a benefit in keeping the restaurants open, in that at least those eating there will eat kosher meat and kosher food. If restaurants were to be closed, there is a concern that visitors will go to non-kosher restaurants instead. Yet, this benefit, in itself, is not sufficient for us to perform an aveirah.
For these reasons, the Teshuvos Ve-Hanhagos (2:257) writes that we cannot permit this, but it is permitted for us to remain silent, and not to make objections to those who open the restaurants. He adds that a restaurant that remains open must put up a note, stating that the meaty foods are intended only for those who are permitted to eat them in the Nine Days (for instance, Sephardim before the week of Tisha Be’Av commences; this year, when Tisha Be’Av is on Sunday, “shavua she-chal bo” doesn’t happen at all).
Shut Pe’as Sadcha (2:119) cites from the Chazon Ish that one should be stringent, but concludes that we should remain silent if asked, because in any case our advice (to close shop) won’t be heard.