Sir: The primary values of our society need to be clearly and openly inscribed in a constitution. Until they are, appeals to shared and fundamental values will lack credibility, and Britain's social as well as economic and political renewal will be indefinitely postponed.

Joshua Rozenberg's attack (letter, 4 August) on Polly Toynbee misses this point and is also misleading. Ms Toynbee arguedthat judges are now making up our constitution as they go along. Often to our benefit, perhaps, but it is no way to run a country and, she concludes, we should have a Bill of Rights and a written constitution. Rozenberg's riposte is that because a Bill of Rights would have to be interpreted by judges, it would give them more power anyway and, he implies, thereby make the problem worse.

Our judges exercise a growing constitutional role because of the nature of modern government. This is unavoidable and inescapable. The issue is not whether they should have constitutional power but how they exercise it and on whose authority.

Reformers argue that they should exercise it under clear written principles, ones that explicitly clarify and limit their role. The powers of our unwritten constitution are also interpreted and applied; and, because they are not written down, they are altered in ways that are unaccountable and encourage the abuse of power.

One senior civil servant told Professor Peter Hennessy that the constitution was "something we make up as we go along". No one should have this power, whether politicians, judges or civil servants.

Yours sincerely,

Anthony Barnett

Charter 88

London, EC1

8 August