Is it permissible for a Muslim to open a restaurant allowing "BYO" (Bring Your Own Alcohol) option for customers?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

First of all, you should know that it is not permissible for a Muslim to allow disobedient people to consume intoxicants in his restaurant or home, or to sit at a table where alcohol is served. If one allows them to do so, it means that he is pleased by what they do and he helps them in disobeying Allaah. Allaah Says (which means): {Help you one another in virtue, righteousness and piety but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment.}[Quran 5:2]. Moreover, the Prophet said: "Whoever believes in Allaah and the Last Day should not sit at a table where intoxicants are served." [At-Tirmithi and Ahmad] Giving the choice for customers to bring their own intoxicants is considered as being pleased with what they do and helping them in committing this great major sin. On the contrary, you are obliged to prohibit them from drinking intoxicants in your restaurant as a way of carrying out the duty of enjoining good and prohibiting evil. Indeed the scholars stated that one should forbid the non-Muslims from committing a sin [when they manifest it].

As-Safaareeni from the Hanbali school said: 'If they manifest an act that is a sin in our religion, it is an obligation to deny them from committing it, and if it is an intoxicant, it is permissible to pour it on the floor.'

We know that in your country you cannot personally dispose of all intoxicants, but if you are able and have the choice not to allow intoxicants in your restaurant, then it is an obligation to do so. If this is not possible, it is still not permissible to declare that any intoxicants can be consumed there, as doing so is being pleased with this and it is considered as inviting sin to be committed. If it is not possible to prevent the consumption of intoxicants in your restaurant then at least do not voluntarily allow them to bring it there, and you should sell your restaurant and look for another permissible means of attaining provision and Allaah Has facilitated many means for attaining lawful provisions.

Allaah Knows best.