Jacob Gersen & Eric Posner have posted Soft Law on SSRN. Here is the abstract:
Soft law consist of rules issued by law-making bodies that do not comply with procedural formalities necessary to give the rules legal status yet nonetheless may influence the behavior of other law-making bodies and of the public. Soft law has been much discussed in the literatures on international law, constitutional law, and administrative law, yet congressional soft-lawmaking, such as the congressional resolution, has received little attention. Congressional soft law affects behavior by informing the public and political institutions about the intentions and policy preferences of Congress, which are informative about future hard law as well as of Congress’s view of the world, and thus relevant to the decision-making of various political agents as well as that of the public. Congressional soft law is important for a range of topics, including statutory interpretation and constitutional development. Other types of soft law – international, constitutional, and judicial – are compared.
And a bit more from the text:
Consider an agent that has law-making powers. The agent could be a legislature, a common law court, an administrative agency, a government that participates in international law-making, or a similar entity. Authoritative documents such as written constitutions, and unwritten customs, set the rules that determine when the agent’s communications are taken to be law and when they are not taken to be law. When the agent complies with the rules, then other agents— typically, those with executive power—will treat the communication as law, and act in conformity with it. They will arrest people who break the rules, or enforce civil damage judgments. The public will react accordingly.
When the law-making agent does not comply with the rules, its communications will not be treated as law. Executive officials will not arrest or otherwise sanction people whose behavior is inconsistent with the policy judgment reflected in the communication. However, the public (and other political agents) will often react as though the communication were in fact law, as we have argued. The public might bring its behavior into conformity with the policy goals expressed in the communication because (for example) it predicts that later the law-making agent or some other law-making agent will convert the communication into law, or because the pronouncement is a focal point for behavior. As behavior changes, it may become easier for the original law-making agent to enact a hard-law version of the soft law, or for some other law-making agent (such as a court) to convert the soft law into hard law.
A hypothesis follows from this analysis. All else equal, the relative importance of soft law to hard law—at the risk of spurious precision, we might say the ratio of soft law to hard law—will rise as the formalities for creating hard law become stricter. This hypothesis explains the high soft law content of international law, where hard law requires the consent of all affected states; and of the common law, where hard law can be generated only in response to a justiciable dispute; and of constitutional law in the United States, where hard law can be created only through the strict Article V process or in response to justiciable disputes. Our topic—statutory law—is the one where hard law is easiest to create; but as we have seen, it is hard enough to create that various soft law substitutes—concurrent resolutions, hortatory statutes, signing statements—have emerged. One might also predict that soft law will become popular in periods of uncertainty, where law-making agents might seek to test the waters of public opinion before committing itself to a hard-law enactment.
Highly recommended. An important paper.