With law-governed multi-agent systems complexity growth, it is harder to design and implement requirements related to dependability mainly because there is no control point over such systems. Despite the great importance of those problems, there is no solution that fully addresses those issues in the context of law-governed multi-agent systems. However, there is a fault tolerant technique called Agent Replication that proposes the reuse of some recovery concepts of distributed systems through a fault tolerance based approach on some data that helps the identification of critical agent. And, besides the existents strategies of agents´ criticality estimation, none of them presents the granularity degree necessary for the monitoring of law- governed open MAS´s. Due to it, the goal of this work is to present a mechanism of the configuration variation of the agents´ criticality that interacts in open MAS´s. To achieve this goal, an architecture to support the development of fault tolerant law-governed open MAS and an approach to design such mechanisms with simplicity, modularity and reuse were proposed. This work has three main contributions: an extension on the conceptual model of the law- specification declarative language XMLaw within new elements to monitor the agents´ criticality; the integration of two frameworks: one is for law-enforcement (M-Law), and the other one is for a dynamic and adaptative agents´ replication (DimaX); and a proposal of a means to document and derive the laws. Finally, we present some sheets of the results of the proposed mechanism application in two case studies.