Is it permissible to reject the engagement of a man who works as an administrative public prosecutor, despite the family's approval, based on the suspicion of the impermissibility of working with man-made laws, especially if the suitor believes it is permissible out of obedience to the ruler?

The first is to marry a woman to a man of religious commitment and good character. If a man whose religious commitment and character you approve of proposes, then marry her to him, otherwise, there will be tribulation on earth and widespread corruption. The man mentioned in the question is not suitable for marriage, despite performing his religious duties and being kind, because his profession involves ruling by man-made laws, which is forbidden. At the very least, even if he does not consider ruling contrary to God's law permissible, it is a grave sin. It is advisable to reject this suitor. And whoever fears Allah - He will make for him a way out and provide for him from where he does not expect.