In multi-Agent systems, norms are being used to regulate the behavior of the autonomous agents. Norms describe the actions that can be performed, must be performed, and cannot be performed in the system. One of the main challenges on developing normative systems is that norms may conflict with each other. Norms are in conflict when the fulfillment of one norm violates the other and vice-versa. In previous works, the conflict checkers consider that conflicts can be detected by simply analyzing pairs of norms. However, there may be conflicts that can only be detected when we analyze several norms together. In this paper, we present a conflict checker that is able to check direct conflicts among multiple norms and a strategy developed to minimize the complexity of such problem, since the checking of multiple norms is a NP-hard problem. The algorithms are presented, a discussion about its complexity is provided and the validation of the conflict checker is described.