I will focus on the advantages of soft law in order to understand the reason why it became such an important tool in international law in the recent decades. Before starting I will define the term soft law. The notion describes international instruments that their makers recognise are not treaties and which are not intended to create legal rights and obligations. The idea is based on the presupposition that we need complementary normative instruments in order to regulate the multi-dimensioned problems of our contemporary world.
Firstly, as Anthony Aust puts it, there is a lack of formality with non-binding instruments. As a consequence, while an informal instrument becomes effective on signature or at a fixed date, a treaty can only become effective upon domestic ratification, which can take a long time. For example the Rio Declaration on Environment and Development could achieve universal participation in such a short period of time only due to its character of soft law.
Secondly, because it is not a treaty it is not required to be registered pursuant to article 102 of the UN Charter, nor to be published in the official journal of the signatory state. As a result, soft law arrangements are preferred especially in the defence field, where confidentiality is essential for reasons of national security.
Thirdly, if an informal instrument contains provisions for the settlement of disputes then it usually provides for settlement of dispute through negotiation between the parties (no referral to any court or third party).
Another, and probably the greatest advantages of a soft law instrument is its flexibility, or in other words, the simplicity with which it can be amended. Any amendment can be effected with the same velocity as the conclusion of the instrument itself. In the case of arrangements with complicated technical or financial provisions there is usually a need to make frequent modifications. Examples for this would be the Food and Agriculture Organization’s Code of Conduct on Responsible Fisheries, which was further developed by non-binding instrument.
Chinkin points out another feature of soft law, namely that it can be used as compromise between states which did not favour a regulatory instrument and states which would have preferred a treaty. Furthermore, another important advantage of soft law is that it can influence international politics.
Finally, for termination a period of notice is commonly required which is less than for treaties. It could also be argued that no notice is required, because it is not a legally binding instrument. According to Aust if the instrument is supplementary to a treaty and has no termination clause, then termination depends upon its purpose. If it is essential for the implementation of the treaty, the arguments against termination of the informal instrument are stronger.
To conclude I would like to mention that the major shortcoming of soft law is also its greatest strength, the fact that it is non-binding guarantees its speed, flexibility, simplicity and confidentiality.
 Aust2, p.11.
 Oppenheim, pp.899-900
 Aust, p.789.
 Evans, p.125.
 Aust, p.792.
 Aust, p.791.
 Evans, p.125.
 Shaw, p.111.
4. L. Oppenheim, International Law, Eighth Edition (Oxford: Oxford University Press, 1956), hereinafter: Oppenheim.
2. Food and Agriculture Organization’s Code of Conduct on Responsible Fisheries, hereinafter: FAO’s Code of Conduct on Responsible Fisheries.
3. Rio Declaration on Environment and Development 14 June 1992, hereinafter: Rio Declaration.