The law consists of, most simply, rules for the conduct of individuals within a group. For a man or woman on a desert island alone, law would serve no purpose. Behavioral dos and don’ts are law’s social function. If members of society do not follow the law, there is chaos or conflict, or both. Ignored, laws are ineffective. But laws work because they are not ignored but heeded. From yield signs to the tax code to contracts to zoning codes, people follow the law. Why?

In The Expressive Power of Law, Richard H. McAdams, the Bernard D. Meltzer Professor of Law at the University of Chicago Law School, tackles that question and puts a new twist on what have been its familiar answers. One of the conventional theories of legal compliance is deterrence: people follow the law to avoid the sanction imposed for not doing so. Don’t steal because you don’t want to go to jail; don’t speed because you don’t want to pay a fine; don’t breach the contract because you don’t want to get sued and lose. Alternatively, some legal theorists contend that compliance with law comes from the population’s perception of the law’s legitimacy. Following the law is a duty and violation of the law a moral failing, some argue. These two conventional accounts of legal compliance—deterrence and legitimacy—have graced page upon page of legal journals, with economists generally decrying the later in favor of the former, and sociologists generally flipping that order.

To this somewhat esoteric battle comes McAdams carrying the cause of “law’s expressive power” as an explanation for a population’s compliance with laws. In a tightly written and compelling introduction, McAdams lays out his thesis and explains that the expressive power of the law supplements and does not displace deterrence and legitimacy as the basis for compliance.

Read more at Evolutionary Studies in Imaginative Culture