The jurisprudential rule of "legal permission does not negate the guarantee" is one of the well-known rules in Imami jurisprudence; in contrast to this rule, there is a view that, based on the principle of "legal permission negates the guarantee", considers legal permission to be an obstacle to the realization of the guarantee in some cases. The present study, with a descriptive-analytical approach and a library method, seeks to extract and systematize the foundations of this view in the scattered opinions of prominent Imami jurists; the findings of the study show that the evidence for this theory is based on four main axes: narrative evidence; rational arguments based on the rule of goodness and ugliness, continuous rational behavior; and transmitted consensus. An analysis of these principles shows that the theory of "negation", beyond a case exception, has a coherent theoretical structure and is aligned with the rule of permission, which is rooted in justice and legal logic. This study, while systematizing this scattered evidence and providing an analytical framework for subject differentiation, explains the limits of the application of the famous rule and emphasizes the need to review its scope.