SIR - Theresa May told her cabinet that the use of chemical weapons in Syria showed an erosion of international legal norms. She is obviously referring to legal norms for the powerful and not civil society.

There are de facto two moral codes operating in most countries: the law the vast majority has to abide by and a law that permits the powerful to transcend this law and commit otherwise illegal acts with impunity.

There are, of course, many countries in the world with their own codes of behaviour but all conform, more or less, to a worldwide standard of basic morality - for the common people. So why this second code for the powerful?

Historically, the powerful have been adept at modifying rules that apply to the rest in pursuit of their own interests. They have used the instruments of state to justify to themselves and their agents the rightfulness of their actions. Nevertheless, it is illogical to have conflicting moral codes.

There is an empirical reason why all civil societies' moral codes conform to a global pattern: it is because morality is intrinsic in the human make up. We depart from its precepts with peril.

Geoff Naylor, Birch Close, Winchester