Which action would violate the concept of rule of law?

The rule of law implies rule according to law. It also implies that the government must rule under the edicts of the law. As such, may act unilaterally or arbitrarily outside the confines of the law. The government should not therefore demand civil damages or undertake criminal punishment without strict adherence to the well established and clearly stated laws and procedures. As such, doing anything contrary to this violates the concept of rule of law.