The Soft Law Threshold
Of course, any normative statement, irrespective of source, has some possibility of becoming a rule of international law. An idea proposed by a student in a university lecture hall, a proposition from a political party manifesto, a tenet of religious faith, a dictum in a national court decision, a normative assertion set forth in a human rights NGO’s advocacy document, or a rule formulated by a transnational working group of law professors. Any of these could be the genesis for an eventual rule of soft law.
However, a normative statement will be considered a rule of soft law only once it acquires a degree of traction. For purposes of this study, the term soft law refers to rules that are already in the process of incubation, that are emerging rules of international law, that are viable candidates for crystallizing into hard law. This traction must come in the form of acceptance by the authors of international law—states.
Any attempt to define this point of traction raises a number of further questions. How much acceptance is sufficient to meet this threshold, in terms of degree, directness, and proximity? Can the necessary support be expressed through intergovernmental bodies, and, if so, what are the criteria for determining the necessary institutional pedigree and what is the necessary degree of proximity between the intergovernmental body and the will of states? Will the requisite degree of acceptance vary based on the character and function of the norm at issue, for example whether it is a new rule emerging in a sparsely populated field, or whether it is a refining rule in a densely regulated area of international law? Must there be affirmative support, or express acceptance, or would mere acquiescence suffice? Does the burden of inertia shift, and if so, at what point, in what contexts, and based on what factors?
No precise lines can be drawn, and any analysis would be highly context dependent. Just as it is impossible to come up with a precise formula for determining when a rule of soft law has crystallized into hard law/2 so it is impossible to define with precision the moment at which a proposed rule has achieved sufficient traction to fall within the category of soft law. 
The principal and essential factor, of course, is acceptance by states. At least some degree of state acceptance is necessary for a norm to be considered soft law as defined here. Other, related factors might include: the intent of the authors, the proximity of the authors to states, the number and representativeness of states involved, institutional pedigree and imprimatur, the normative character of the rule as formulated, whether the rule is formulated in terms of rights or obligations, the nature and form of the instrument in which the rule appears, whether the new rule is framed as an interpretation of an existing rule, and the character and status of those to whom the rule is addressed. These additional factors may themselves indicate state acceptance, or may influence the degree of state acceptance regarded as sufficient to establish the rules as soft law.
As soft law in the strict sense comprises the norms as such, the above factors are not tied to any particular form. Any evidence of state acceptance of the rule would qualify as evidence of soft law. Similarly, any evidence of customary law would also be evidence of soft law, including, for example, the subsidiary means for determining rules of international law described in Article 38(1)(d) of the ICJ Statute.
While there may be vast differences of opinion regarding the point at which a rule satisfies the definition in section 3, the purpose of this chapter is simply to clarify our general conception of soft law. Thus, the only criteria used to delimit the concept of soft law for the purposes of the present study are that the content be formulated as a rule and that the rule has acquired traction, and, as such, is in the process of incubation.
-  The law is in a constant state of flux. This is particularly true of international law. Attempting toascertain and interpret the applicable rules of international law in a given factual context at a particularmoment in time is like trying to paint a picture of the precise location of an object that is constantlyin motion.
-  A recent example of this ambiguity would be the so-called Copenhagen Process Principles andGuidelines. The Principles and Guidelines were created in an intergovernmental setting, but with limited participation. The Principles were drafted in consultation with, and ultimately acknowledged by, aselect group of states invited by Denmark to participate in a conference for this purpose. The Principlesexpressly declare that they do not alter the applicable rules of international law. It would seem thatsuch a caveat would preclude these principles from qualifying as soft law by their simple formulationand acknowledgement by states. However, at least one domestic court has subsequently invoked thePrinciples in support of interpreting and applying rules of international humanitarian law. Could thismanifestation of state acceptance be sufficient to bring the cited Principles into the realm of soft law?The Copenhagen Principles are discussed in the chapters by Bruce Oswald and Peter Vedel Kessing inthis volume.