1. A simulation system for testing a simulation of a device against one or more violation rules, the simulation system comprising: a device simulator for executing the simulation of the device using a device design, a device model and a simulation scenario; and one or more violation monitors, one violation monitor for each violation rule, wherein at least one of the violation monitors comprising: a violation information detector for detecting one or more violations of the respective violation rule of the one or more violation rules during the executing the simulation of the device and, for each violation, determining information representing the respective violation of the one or more violations, wherein the detecting the one or more violations comprises comparing a simulated parameter against a threshold, and a threshold controller for determining the threshold for the respective violation rule in dependence on a temporal characteristic of a violation associated with the respective violation rule.