New standards and initiatives in the U.S. electric power grid are moving in the direction of a smarter grid. Media attention has focused prominently on smart meters in distribution systems, but big changes are also occurring in the domains of protection, control, and Supervisory Control and Data Acquisition (SCADA) systems. These changes promise to enhance the reliability of the electric power grid and to allow it to safely operate closer to its limits, but there is also a real danger concerning the introduction of network communication vulnerabilities to so-called cyber attacks. This article advocates the use of a reputation-based trust management system as one method to mitigate such attacks. A simulated demonstration of the potential for such systems is illustrated in the domain of backup protection systems. The simulation results show the promise of this proposed technique.