Identifying which international maritime legal instruments are mandatory or recommendatory is complicated task even for maritime regulatory bodies. Although International Maritime Organization (IMO) had tried to ease the complexity by adopting guidelines on uniform wordings for making reference to other instruments in IMO parent conventions, there has still been some confusion identifying the mandatory status of IMO instruments. The aim of this study was to map out a step-based guideline to resolve the complexity of the mandatory status of IMO instruments to the maximum extent possible. This study reviewed the history of IMO rule-making process to find the root cause of the problem, then analyzed the approaches of regulatory enforcement bodies to check the practices. In conclusion, readers are directed to find such information as to legal status of IMO instruments and an improvement is proposed to enhance the transparency of information sharing for maritime industry to make better informed decisions.

Abstract
1. Introduction
2. Structure and legal status of IMO instruments
    2.1 The relation of Convention and Codes
    2.2 Legal status of Resolutions and Circulars
3. Evolution of IMO rule making process
    3.1 IMO practice before Resolution A.911(22)
    3.2 IMO practice after Resolution A.911(22)
    3.3 Quasi-mandatory IMO instruments
4. Mandatory application of IMO instruments inpractice
    4.1 The role of Flag States in making IMO instrumentsmandatory
    4.2 The role of ROs in making IMO instruments mandatory
    4.3 Four step approach to IMO instruments
5. Conclusions and suggestions
References

• Dong Nam(R&D Center, Korea Maritime Transportation Safety Authority) Corresponding Author