 All the sources reviewed so far, customer international law, treaties, general principles of law, unilateral acts of states and unilateral acts of international organisations, all those sources are clearly binding under international law when the conditions for their coming into legal existence are met. The question to be asked now is whether those formal sources and those formal processes are the only ones by which rules of international law can be created or whether international normativity can also arise through other processes that are probably less formal and less institutionalised but that nevertheless result in instruments having some legal character. The word soft law has been coined to cover this phenomenon. It refers to a wide range of instruments and documents adopted by a great variety of actors. Instruments whose normative status is unclear but which nevertheless carry a certain weight and a certain influence which brings them close to having the status of legal norms. And for instance one can think about technical or industrial standards adopted by associations of certain manufacturers or informal decisions taken by the central bankers of the major economies of the world or tests designed by education professionals in order to rank schools etc. All those instruments, those documents are not legal instruments sensus stricto but they nevertheless exert a great influence across national borders. To a certain extent soft law instruments are complied with and are used as instruments of governance. However the word soft law is ambiguous because it gives the impression that law would exist in various degrees. The law resulting from the processes that we have studied so far would be hard law and the rest all the other documents having some normative pretension would be soft law. The problem is that if law comes in various degrees hard and soft it runs the risk of losing its specificity which is precisely its bindingness. Let me make this clear. There is no doubt that legal obligations can be quite different from each other. For instance an obligation of means is not to be confused with an obligation of result. Despite their variety in terms of what must be done in order to comply with them all those different obligations are nevertheless equally binding in law. The obligation of means is not less binding than an obligation of result if both are for instance to be found in treaties. The problem with soft law is that the notion seems to suggest that there might be some instruments that are less binding as it were than others but that would still be legal instruments and this is problematic and doubtful. Either there is a legal command or there is no legal command. Other obligations are owed as legal obligations or they are not. It cannot really be in between. Sometimes it is very clear that the document at stake is not a legal instrument and this is notably the case when the people drafting the document have no authority to make law. For instance a professional association of manufacturers issuing technical standards for the making and size of bicycle tyres or if they have some authority to make law the drafters have clearly no intention to bind themselves under the law and this is the case for instance when states contract gentlemen's agreements that look like treaties but are on purpose not legally binding or when the G8 heads of states issue a statement or when a world conference makes an action plan to combat poverty in all those cases and despite having eventually a great influence on the conduct of governments those instruments are clearly not legally binding and they do not appartent to any category of law be it hard or soft. But what happens when things are not as clear as that? Should one presume some legal force until and unless it is established that the instrument the document is not binding or should one presume the opposite not legal until proven legal? Well, let me submit that legal certainty requires the latter international law is presumed to come into existence through the formal processes that we have studied while it should be presumed that any other process does not result in the creation of new rules of international law unless otherwise established. This being said some documents that are clearly not legal instruments can not only have a great bearing on the behavior of a variety of actors but they can also be used as benchmarks for the purpose of establishing whether an international law obligation has been duly complied with or not. And let me take an example to make that clear. Under a treaty the riparian states of a river agree that they have an obligation to prevent the pollution of the river and in particular they agree that industrial plants under their control that are discharging effluence in the river should always use the best available technologies. In such a situation and in order to assess whether the obligation to prevent pollution through the duty to impose the use of the best available technologies in industry has been complied with it is necessary to turn to the industry standards. Those standards may not be legally binding instruments but they will need to be referred to in order to assess whether the legal obligation has been complied with or not. Therefore indirectly those standards have a legal bearing but I submit that it would be a wrong conceptual shortcut to consider that they are legally binding as such.