A social norm is a convention implicitly followed by people in a society or community. While it is not illegal to break a social norm, one does so at the risk of public disapproval or ostracism. An example was the social norm for young persons to give up their seats to the infirm, elderly or expectant in public transport, which I observe is much breached today without censure. So that is a norm which is weakening. A more persistent norm is that of saying meaningless pleasantries on greeting an acquaintance and it is part of this norm that an equally meaningless pleasantry is given in reply. Hence, one says, “How are you?” and the other says, “Fine thank you, and how are you?” It would be a breach of this norm to reply by detailing one’s last visit to the doctor for a chronic ailment. People are also expected to look after aged parents. Social norms smooth interactions between people, and common observance of these norms ensure a kind of benign equilibrium for society.

Leaders find their job easier if they do not have to rely strictly on laws to govern their people, but see to it that social norms are maintained. Assuming that people behave according to the norms makes policy planning more predictable. They can then devote their efforts to implementing those policies, some of which may be designed to nudge social norms in new directions, hopefully to the benefit of the people they govern.

The other interpretation is that the norm is one that applies

to the leaders themselves, i.e. a high level set of conventions that people expect leaders to observe. Examples are (i) leaders are honest with the people and (ii) leaders do not live ostentatiously. Breaking such norms is not illegal for the leaders, but the effect of that is the loss of trustworthiness as perceived by the people.