There may be unenforced norms in legal systems. In today’s Turkish law, there are many unenforced norms. The fact that many norms have become unenforced despite being enacted by the legislator makes the concept of unenforcement as well as its relationship with legitimacy worth examining. In this paper, the relationship between unenforcement and legitimacy is examined especially in the constitutional context, through the ‘Broken Windows Theory’, since unenforcement causes further irregularities in legal order. It is concluded that a norm that has lost its legitimacy will become unenforced, that an unenforced norm may cause negative effects in terms of both partial and total legitimacy of the legal system, and that the effect of the unenforced norm on the overall legitimacy may change according to its place in the hierarchy of norms. In addition, it is revealed that in a state of law, unenforced norms should not exist at any level of the hierarchy of norms and that the legislator should establish laws that are compatible with the values, and habits of the people in order to prevent the norm from becoming unenforced and thereby reducing the legitimacy of the legal system.