"The Caliphate and Imamate in Islamic Thought" Series by Writer and Thinker Thaer Salama - Abu Malik - Part 73
As for the separation between the (Executive Authority) and the (Judicial Authority), Islam does not make the judicial authority separate from the executive authority. Often, the judge combined his authority in the judiciary with other executive functions, such as leading the army. In any case, I believe that the separation of the executive authority from the judicial authority is one of the matters whose decision was left to the authority holder. If he sees that the separation between them is the way to ensure the integrity of the judiciary, he separates. If he believes that combining them in one body is faster in implementing judgments, he combines.