What is the ruling on designing a building for an usurious entity, or one that sells alcohol, or a dance hall, or an unjust police station? And what should the engineer do if the manager insists on it?

It is not permissible to assist in the construction or design of buildings intended for prohibited purposes, such as usurious banks and dance halls. However, there is no objection to designing and constructing buildings not designated for such purposes, like police stations and hotels. What is predominantly or intentionally used for unlawful purposes, it is not permissible to assist in, because means share the rulings of their ends. This is based on the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." The engineer must refrain from what is unlawful or assists in what is unlawful, even if his manager insists on it, unless his refusal results in an unbearable harm, such as dismissal from work while he is in severe need of it.