The Khalifah’s adoption is restricted by the Shari’ah rules; he is prohibited to adopt any rule which is not derived according to a legitimate deduction from the Shari’ah evidences, and he is restricted with what he adopted of the rules, and by what he bound himself to with respect to the method of derivation. So he is not permitted to adopt a rule which has been derived according to a methodology which contradicts the methodology he adopted, and he cannot give an order which contradicts the rules that he had adopted.

There are two issues in this article: the first being that the Khalifah is restricted in the adoption of rules to adopting from the Shari’ah rules; in other words, he is restricted by the Islamic Shari’ah in legislation and enacting laws. Therefore, it is not permitted for him to adopt anything which contradicts that since they would be the rules of Kufr (disbelief); if he adopted rules from other than the Islamic rules, and he knew that what he had adopted was something other than the Islamic Shari’ah, then the words of Allah (swt).

“And whoever does not judge by what Allah has revealed - then it is those who are the disbelievers.” (TMQ 5:44) apply to him, so if he believed in the rule that he had adopted, then he would commit disbelief and apostatise from Islam. If he did not believe in it, but he took it upon the basis that it did not contradict Islam, in the same manner that the Ottoman Khulafaa’ acted during their final days, then it would be forbidden for him but he wouldn’t commit disbelief. If he had a semblance of an evidence, such as the one who legislates a rule which has no evidence, due to a benefit that he thinks is there, and relies upon the rule of Al-Masalih Al-Mursalah, or the “preventing the means” or “the means of the actions” or anything similar, then if he thought that these rules were Shari’ah rules and evidences, it wouldn’t be forbidden for him and nor would he commit disbelief. However, he is mistaken, and what he has derived is considered a Shari’ah rule by all of the Muslims, and it is obligatory to obey it if the Khalifah adopts it, since it is a Shari’ah rule, and it would have a semblance of an evidence even if he was mistaken in the evidence, since he is like the one who is mistaken in the deduction from the evidences. In any case, it is obligatory for the Khalifah to restrict his adoption to the Islamic Shari’ah, and to restrict himself to adoption of Shari’ah rules derived by a correct deduction from the Shari’ah evidences. The evidence for this: