Anti-poll tax campaigners said they were "profoundly disappointed" after Mrs Blair - known professionally as Booth - admitted presenting a paper to an enforcement conference organised by the Institute of Revenues, Rating and Valuation Officers.
They also expressed concern over one case reported in the Independent on Sunday in which Martin Jacques, 28, was sent to serve the second half of a 14-day sentence after losing an application for judicial review opposed by Ms Booth for South Ribble magistrates.
Like all barristers, Ms Booth, 40, must obey the "cab rank" principle and accept cases as they come along. As a respected employment and public law specialist, it is inevitable that she should become involved in the enforcement of poll tax arrears. She may not reject cases simply because they contradict her political views.
However, it has also emerged that she spoke at the IRRVO conference in Telford last March on how to apply for orders to jail non-payers. She has also acted for several councils during judicial review proceedings at which opposing barristers have attempted to free defaulters from prison sentences.
Frank Dobson, Labour's environment spokesman, said Labour believed people who could pay should pay, but it was opposed to jailing people who were simply too poor to pay.
The Reverend Paul Nicolson, treasurer of the Campaign Against Poll Tax Imprisonment, said he was "profoundly disappointed in Cherie Booth because I understood that the Labour Party stood for justice. But the imprisonment of people who are poor is a grossinjustice."
Harriet Harman, Labour's employment spokeswoman, said: "Have we reached the stage where wives of politicians have to give up any work other than as appendages of their husbands?" Ken Livingstone, one of the fiercest opponents of the poll tax, said: "WhatCherie Blair does in her professional life is her own business."
Anthony Scrivener QC, a former chairman of the Bar Council, said Ms Booth would have no choice over the types of case she handled. "Taking cases on the cab rank principle is vital in ensuring that people get good representation because it prevents barristers turning down Legal Aid cases, which earn them only about a quarter of those paid privately. Once you have been instructed, you must do your best for your client, whether their political beliefs are the same as yours or not."Reuse content