Constitutional review usually focuses on the positive actions of lawmakers in relation to enacted legislation. However, can constitutional violations arise out of the negative actions of the lawmakers? This situation may be called "legislative omission" which happens when the lawmakers breach their duty to enact laws required by the constitution. If the negative actions of lawmakers can cause constitutional violations, how can this kind of violations be reviewed? The constitutional judiciary may adopt this mission in some countries as a kind of constitutional review, and some other countries regulate specifically the method of practising this monitoring. However, recognising and monitoring this kind of constitutional violation is still relatively new and even identifying this problem is still not clear enough. Thus, this thesis is an attempt to clarify this legal phenomenon deeply by studying several issues related to its definition, types, and identifying the reasons which cause it, on one side. Then it is an attempt to examine the role of the constitutional judiciary to remedy this problem, the kinds of decisions which may be issued by judges in this context and how can this kind of monitoring be justified, on another side.