It must be stated here that the doctrine of merger is a common law doctrine, which is based on the principle of propriety in our present hierarchy of the justice delivery system. It Is not a doctrine laying down a principle of any universal application and merely where there are two orders one of the inferior authority and another by the superior authority passed in an appeal or revision, it would not necessarily mean a merger of the two orders, irrespective of the subject matter or even irrespective of orders passed in the appeal or revision.
 The doctrine of merger has been thoroughly discussed in Kunhayammed and Others Vs. State of Kerala and Another[AIR 2000 SC 2587] by the Hon’ble Supreme Court, where the Hon’ble Apex Court has, inter alia, stated thus:
12. The logic underlying the doctrine of merger is that there cannot be more than one decree or operative orders governing the same subject-matter at a given point of time. When a decree or order passed by an inferior court, tribunal or authority was subjected to a remedy available under the law before a superior forum then, though the decree or order under challenge continues to be effecting and binding, nevertheless its finality is put in jeopardy. Once the superior court has disposed of the lis before it either way -whether the decree or order under appeal is set aside or modified or simply confirmed, it is the decree or order of the superior court, tribunal or authority which is the final, binding and operative decree or order wherein merges the decree or order passed by the court, tribunal or the authority below. However, the doctrine is not of universal or unlimited application. The nature of jurisdiction exercised by the superior forum and the content or subject-matter of challenge laid or which could have been laid shall have to be kept in view.