Originally Posted by
RHINO
If it is in the MEL then it is the Captains decision.
If the aircraft requires a transit/daily inspection before the next flight and it needs to be certified by a ground engineer/mechanic then he/she will make the decision. If checking that the nav lights are working is on the transit/daily check list then its a no go.
The Captain can jump up and down all he/she likes but if the engineer/mechanic refuses to sign it off you're going nowhere unless a written dispensation arrives from your company quality department. Or you get it fixed.