Safety requirements are important constraints. The safety team has to work out all the hazards and faults which could which could threaten safety. They do this by analyzing the functions, and later the design, of a system. They consider how likely each hazard is, what can be done to reduce the risk that it will happen to an acceptable level, and what to do if it happens. They also combine all the hazards to estimate how safe the whole system is. Now this is a specialized task. Obviously, it is a good idea to keep safety engineers can work on them while the system designers work on the system itself.