So I am in doubt about this :
Can buildings fire overwatch when there is an enemy unit within 1"?
The rules involved:
Immobile: This model cannot move for any reason, nor can it fight in the Fight phase. Enemy models automatically hit this model in the Fight phase - do not make hit rolls. Howvver, this model can still shoot if there are enemy models within 1" of it and friendly units can still target enemy units within 1" of this model
overwatch rule:
Each time a charge is declared against a unit, the target unit can immediately fire Overwatch at the would-be attacker. A target unit can potentially fire Overwatch several times a turn, though it cannot fire if there are any enemy models within 1" of it. Overwatch is resolved like a normal shooting attack (albeit one resolved in the enemy's Charge phase) and uses all the normal rules except that a 6 is always required for a successful hit roll, irrespective of the firing model's Ballistic Skill or any modifiers.
I ruled that , as the immobile rule does not state that it includes overwatch, it does not affect the overwatch rule, just normal shooting. But the overwatch rule states it is resolved as a normal shooting attack, my opponent was saying that if it can fire normally when there are units within 1", why would it not be able to fire overwatch, which are also shooting attacks...