A sound theory of social norms thus should address two levels of decision and choice: the individual level and the societal (or group) level. Current theory addresses only the individual level, however. But why? The above excerpt from North (1990) shows that the omission of the societal level of analysis is not an accident. North emphasizes that he seeks to anchor the theory of social institutions in individual choice because this would link this theory to the entire body of neoclassical economics.
He is Amir Litch (725: 2008) in his article "Social Norms and the Law: Why peoples obey the law". The North's excerpt he refers to is in pages 722-723.