Explanation of the author's statement: "A free, Muslim, just man"

The Shaykh : The fourth condition is that the judge be free, the opposite of which is a slave. It is necessary that he be fully free. The reasoning for this is, first, that a slave is generally considered deficient because he feels he is below others; you do not find him comprehending things or looking at them with seriousness. This is the case in most instances. Second, a slave is occupied with serving his master, whereas judging requires dedication to examining rulings between people. This is the reasoning. There is no evidence from the Book or the Sunnah that prevents a slave from being a judge. Therefore, the stronger opinion is that a slave is valid as a judge if the conditions of judging are present in him, namely strength and trustworthiness. If he has knowledge, trustworthiness, and truthfulness, what prevents him from being a judge? As for the reasoning that he is occupied with serving his master, we say: if his master permits him to be a judge, where is the occupation? Yes, if his master refuses to let him be a judge, he has the right to do so, and in that case, it is prevented that the slave be appointed—not because he is not qualified, but because he is owned by another. So, this condition is not actually a condition; rather, slavery is a barrier only because he is occupied with serving his master and considers himself deficient compared to others, and so on. This is reasoning, but it is not consistent. For some slaves, if Allah grants them knowledge, they know their status among people and become muftis and teachers, benefiting the servants of Allah. The fifth condition is that he be Muslim, the opposite of which is a disbeliever, whether he is from the People of the Book or not. It is not valid to appoint a non-Muslim as a judge, because if a non-Muslim takes charge of judging, by what ruling will he judge? By other than what Allah revealed? Allah the Mighty and Majestic commanded that we judge between people by what Allah the Mighty and Majestic revealed, which is the truth. The apparent statement of the author is that this applies even if it is over a non-Muslim community. For example, if the dhimmis are under the rule of Muslim authorities, it is not permissible for the one in authority to appoint a judge of their religion; rather, he appoints a judge from among the Muslims. However, if they themselves resort to one of their own and appoint a judge among them, we do not interfere with them. But for us to appoint a judge over them in the name of the Caliph, the Caliph of the Muslims, this is not permissible. It is also required that he be "just", the opposite of which is an open sinner. Who is an open sinner? An open sinner is one who persists in a minor sin or commits a major sin and does not repent from it. If we find a person who shaves his beard, but he is a scholar and strong, we do not appoint him as a judge. Why? Because of his open sinfulness. If we find a person who lets his garment hang below the ankles, we do not appoint him as a judge because he is an open sinner. If we find a person who backbites people and eats their flesh...