Alberto Gonzales, a former White House counsel and judge in Texas, is an old Bush crony. But after a gruelling five-hour appearance before the Senate Judiciary Committee last month in which he, close to 100 times, disclaimed recollection or knowledge of key events, questions linger about his credibility and competence in handling the dismissals of eight US Attorneys - local federal prosecutors who handle public prosecutions in the 50 states. The Attorney-General may have endured a withering cross-examination but he obtained the one vote of confidence he needed - that of his friend, the President of the United States.

US Attorneys enjoy a special role in the American justice system. Appointed by the President, and confirmed by the Senate, for a four-year term, they may be removed at any time for any reason - even if the President doesn’t like the ties that they wear. But, traditionally, the US Attorneys have been thought to be independent of Washington in handling their own litigation. This is because they have more control over life, liberty and reputation than any other public official. They can order arrests and, on the basis of a one-sided presentation to a grand jury, can cause a citizen to be indicted and held for trial. If they obtain a conviction, their recommendations are given great weight in the imposition of sentence or even parole. They are, in effect, princes of prosecution.

President Bill Clinton replaced wholesale 93 Republican-appointed US Attorneys when he came to power in 1993; but, unless it is a case of incompetence or malfeasance, it is customary for the President to retain a US Attorney he has appointed for the duration of his or her term in office. Gonzales got rid of eight prosecutors appointed by President Bush. At first he claimed that the dismissals were performance-related; then he drew a blank on the reasoning behind the dismissals when tell-tale e-mails coming out of the Justice Department and the White House suggested a political purge.

President Bush has tried to centralise control over the local prosecutors. The Administration, it appears, would like to see more voter fraud, immigration, child pornography and death penalty cases, fewer investigations of prominent Republicans and more indictments of Democrats - particularly during an election season.

Among the more questionable firings were:

Carol Lam, a highly experienced and effective US Attorney in San Diego. She had won the conviction of Randy (“Duke”) Cunningham, a Republican Congressman, on charges of corruption in military contracting and was investigating Jerry Lewis, also a Republican Congressman. Gonzales complained before the Senate that she had not brought enough border crime cases.

John McKay, a well-regarded federal prosecutor in Seattle. The Justice Department at first said that his dismissal was “performance-related”. But McKay had received a favourable evaluation seven months before he was fired, and the Administration had sought to appoint him as a federal judge as late as August last year. The real story behind the dismissal appeared to be the irritation of Washington State Republicans that McKay had refused to start a grand jury investigation of voter fraud in the 2004 gubernatorial election where the Democrat won by fewer than 200 votes.

David Iglesias, of New Mexico, a latecomer to the hit-list. He had an investigation going of Manny Aragon, a Democratic leader in the State Senate, in connection with a conspiracy to skim $4.2 million (£2.1 million) in public funds. Two Republican members of Congress contacted Iglesias and asked him to file a public indictment before the November election last year. Iglesias refused.

Bud Cummins of Arkansas. He was investigating Governor Blunt, the Missouri Governor, over possible corruption in a obtaining state licenses. Gonzales wanted to replace him with Tim Griffin, a former aide to Karl Rove, the White House political strategist.

As if this were not enough to discredit Gonzales’ judgment, there were the circumstances surrounding those who the Attorney-General decided to retain:

Stephen M. Biskupic, a Milwaukee prosecutor, who was on the hit-list until he agreed to prosecute Georgia Thompson, formerly an official in the Administration of Wisconsin’s Democratic governor. The Court of Appeals was so troubled by the insufficiency of the evidence against Ms Thompson that it summarily threw out her conviction.

Patrick Fitzgerald, the US Attorney in Chicago. Fitzgerald was appointed special prosecutor in the White House leaks investigation that led to the prosecution of I. Lewis "Scooter" Libby, chief of staff to Dick Cheney, the Vice-President, for perjury and obstruction of justice.

Kyle Sampson, Gonzales’ chief of staff, who was in charge of the dismissals, testified that he had added Fitzgerald to the “to-be-fired” hit-list, only to regret the suggestion and withdraw it immediately. This led Senator Schumer of New York to call the notion of firing Fitzgerald in the middle of the Libby case a “hair-brained scheme” and to ask the trenchant question, “Did anyone suggest that maybe after that suggestion you shouldn't be in charge of firing US attorneys?” The chief of staff, along with two other high-ranking Department of Justice officials, resigned.

The circumstances of the firings are troubling. US Attorneys are supposed to bring cases based on the facts and the law - not to punish the political enemies of the party in power. The Attorney-General who supervises them may properly direct prosecutorial priorities, but not (except in extraordinary circumstances) the conduct of particular cases. Attorney-General Robert Jackson, later Supreme Court Justice and Nuremberg prosecutor, elaborated the delicate balance when he addressed a meeting of US Attorneys in 1940: “Your responsibility in your several districts for law enforcement and for its methods cannot be wholly surrendered to Washington, and ought not be assumed by a centralised Department of Justice … Experience, however, has demonstrated that some measure of control is necessary. In the absence of it different district attorneys were striving for different interpretations of applications of an Act, or were pursing different conceptions of policy. Also, to put it mildly, there were differences in the degree of diligence and zeal in different districts. To promote uniformity of policy and action, to establish some standards of performance, and to make available specialised help, some degree of centralised Administration was found necessary.”

Just where “centralised administration” ends and vindictive political prosecution begins is the place where many say Attorney-General Gonzales dropped the ball. Meanwhile, most Americans polled, as well as influential legislators of both political parties, including most notably Republican Presidential hopeful, Senator John McCain of Arizona, have called upon Alberto Gonzales to resign.

James D. Zirin is a trial lawyer in New York.

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