The plan to enshrine in statute the independence of the judiciary, praised last week by Scotland's most senior judge, was described by a former solicitor-general yesterday as "not worth the paper it's written on".

Lord Hamilton, the Lord President told the Holyrood Justice Committee last week that the proposal in the Judiciary and Courts (Scotland) Bill "sends out the right message" against a day in the future when "conflicts could arise between the judiciary and the executive".

But yesterday retired judge and former law officer Lord McCluskey told the same committee: "The evidence you heard last week was, with respect, naive. The simple answer is it could never be more than symbolic, because if an unpleasant government came to power, then do you imagine it would not behave like the governments in Zimbabwe or Pakistan?

"If a party comes to power which does not respect democratic values then this is not worth the paper it is written on. Just as this Parliament could pass it a week on Monday, it could repeal it a week on Tuesday. This is actually worth nothing at all."

Lord McCluskey added: "Most countries in the world have a written constitution in which the independence of the judiciary is embedded in the constitution. Judicial independence lies in the hearts of men, not in constitutions and statutes of this kind, and I would rather it stayed there."

Calling the proposal "just a kind of gesture politics", he said: "The English needed it and so we slavishly copied the English. We have never had a statutory declaration in Scotland. We don't need to follow slavishly and plagiarise English legislation."

The bill would give the Lord President formal recognition as the head of the Scottish judiciary, making him responsible for matters such as the training, welfare and conduct of the judiciary. There would also be new procedures for appointing and disciplining judges and for dealing with public complaints.

The legislation also sets out proposals for modernising the machinery for sacking judges and sheriffs on the grounds of unfitness for office. They would be investigated by a tribunal chaired by a judge and containing a lay element.

Lord McCluskey said: "In my time there have been judges on the High Court bench who drank too much, who didn't do their homework, who didn't turn up. They were dealt with by the Lord President behind the scenes, and dealt with successfully, and that's the way it has to work."

On attracting a wider cross-section of society to the Bench, Lord McCluskey said: "I can see merit in the government, whether through the (judicial appointments) board or otherwise, taking steps to enable more people to acquire the skills that are needed to be a judge.

"But if I'm going to be operated on by a brain surgeon, I want the brain surgeon to be the best brain surgeon. I don't want him operating because he's black, Jewish, Catholic.

"It's the same with judges. It's the same kind of expertise which is required. I don't think affirmative action has any place in the selection of brain surgeons or High Court judges."