His comments, in an interview with the Independent, are certain to fuel an increasingly acrimonious argument over the Government's plans to cut back on the cost of helping people with their court cases.
Reacting to the Lord Chancellor's claims, one solicitor accused ministers of 'arrogance' and said the public had been 'conned'.
Lawyers estimate that as a result of the cuts, 7 million people will lose their right to free legal advice, while millions more will have to pay sharply increased contributions if they find themselves in court.
In the interview, Lord Mackay said such measures were needed because 'it's necessary for the Government as a whole to control public expenditure. I have to cut my cloth according to what is available to me'.
His legal aid budget had risen 'unacceptably' as more people went to court and lawyers took longer preparing their cases. In 1988-89, pounds 475m was spent on legal aid: in 1992-93 the figure would be about pounds 1,100m and would continue to increase by about 10 per cent a year, even after the cuts.
'Why should the taxpayer be more willing to contribute his or her money to help your case than you are yourself, assuming you're in a position to make a contribution?' he said.
In an effort to stave off the cuts, the Law Society, representing solicitors, and the Bar Council, representing barristers, offered to accept a pay freeze and a restriction on the number of lawyers attending court hearings, a package which would have yielded savings of pounds 43m this year.
These proposals do not appear to have found favour with the Lord Chancellor, however.
'What I fear is that, so far anyway, they haven't produced proposals which I could rely upon as likely to reduce the cost (of legal aid). But there's no reason why they shouldn't seek to put them into effect and see what happens,' he said.
In the interview, Lord Mackay added that he was studying ways of making a new privacy law affordable to ordinary people, a move which Sir David Calcutt QC, urged the Government to consider in his recent report on the press.
'I think that it (a privacy law) is a matter that certainly requires to be looked at carefully because I think it is a way forward in the present situation.'
Most observers say it is highly unlikely that the Government will provide legal aid for people who claim their privacy has been infringed, but ministers might offer instead a short, summary procedure in an attempt to settle disputes of this nature cheaply.
Responding to the Lord Chancellor's comments, Stephen Gilchrist, chairman of the Legal Aid Practitioners' Group, said the cuts were 'an absolute scandal'.
The public was being 'conned' by a government which talked of enhancing rights through the Citizen's Charter, but denied people the chance of enforcing them by cutting back on legal aid.