 Social institutions, including legal institutions and military, police, and correctional organisations, have both a massive collective inertia and a massive collective momentum by virtue of the participation in them of many agents over a long time who: (a) pursue the same goals; (b) occupy the same roles and, therefore, perform the same tasks and follow the same rules and procedures, and; (c) share the same culture. Accordingly, social institutions and their component organisations are like very large ocean liners that cannot slow down, speed up, or change direction very easily. It follows that very careful thought needs to be given to the establishment of any additional structure of roles and associated practices that is to be woven into the fabric of the institution. For such an additional (embodied) role structure, once it becomes, so to speak, an integrated working part of the larger institution, is likely to be extremely difficult to remove; it is now a beneficiary of the inertia of the institution. Moreover such an additional, but now integrated, role structure participates in, and influences the direction of, the institution; it is now a contributing element to the momentum of the institution.