At the very top to are citizens with great political power and unfathomable wealth or influence. Members of congress are in that category as are presidents and those who contribute heavily to political campaigns. Those who live at these higher levels can normally commit any crime without ever being prosecuted or punished. Impunity from the law is not gained by some agreement or by joining a group. Basically folks at this level need each other and have common goals and aspiration. The friendships, allegiances and associations they have with one another evolve naturally. Every now and then one or more of these anointed types does end up facing justice.
Why did Bernie Madoff end up in prison? Madoff did something that made the group he belong look bad. Why have Harvey Weinstein’s friends and colleagues turned against him? He is no longer an asset to his peer group. His presence threatens the aspirations and agendas of his associates. Why is Hillary Clinton still sitting on her high perch and still living above the law? Her presence within the elite is still not threatening enough to them to justify throwing her overboard. It could happen and in time we will know.
Those who live above the law complement one another’s agendas. When that changes, especially where other elites might be damaged, by one of the others behavior, the law is then applied to that one person. To be a member of the small elite group when dictates policy to governments around the world no harm must be done to the group as a whole.
None of this is by formal agreement. Given the laws of dominance and subservience that govern the universe, it just morphs out that way.