The contract differs in all societies but is binding upon all in that society. Natural law takes precedence over civil law, custom and even divine law. A family or a ball team is a group but a row of workers on an assembly line or a set of slaves or prisoners working at a task is not a group. In colleges, sororities and fraternities are organized as groups while classes are often impersonal and interactively barren. Central to all group activity is symbolic interaction in which intersubjective understanding emerges.
Groups often have status hierarchy which also pre-shape behavior of members.
Then there are 'dis-engagement' activities in which people recognize that the claims each has on the other are to be set aside until the next time the 'group' meets. They use a variety of tools to maintain a false peace in which food and profits flow from the poorest, hungriest countries in the world to the richest. In the global stratification system, these seven are joined by some 20 or so societies with advanced industrial capacity which extract wealth and food from some 120 or so 'under-developed' countries. A put-down term used to ridicule the ability of people to affect ways of thinking, feeling and acting of each other within a group setting. A judgment on the part of others that one has done something legally prohibited or something morally reprehensible.