By Dan Griffiths
BBC News, Washington DC
For some, Ashcroft was the domestic war on terror's architect
John Ashcroft is a man who divides opinion in America.
To his supporters, he was the Bush administration's chief architect of what the US authorities called the domestic war on terror.
But to his critics, he undermined liberties in the US in a way that had not been seen since the internment of thousands of Japanese Americans after the attacks on Pearl Harbour in 1941.
His successor, Alberto Gonzales, has achieved success the hard way.
Born the son of migrant workers, he grew up in a humble two bedroom house in Texas before going on to Harvard Law School.
A confidant of President Bush, Mr Gonzales served as a Texas Supreme Court Justice when Mr Bush was governor and followed him to Washington to become White House legal counsel.
Mr Ashcroft was chosen by Mr Bush after failing to win re-election as US senator for Missouri in November 2000.
That was despite the fact that his opponent, Governor Mel Carnahan, had died in a plane crash three weeks earlier.
Mr Carnahan's widow, Jean, accepted appointment to the Senate in her husband's place.
Mr Ashcroft is a conservative Republican and devout Christian. His nomination was opposed by many Democrats in the Senate, leading to a bruising confirmation battle that the Republicans won by a slim margin.
Once in office, Mr Ashcroft was quick to make his traditionalist views known in the Justice Department - having two partially nude statues covered up so he would no longer be photographed in front of them.
Alberto Gonzalez in a trusted adviser to President Bush
If confirmed by the Republican-controlled Senate then 49-year-old Mr Gonzales, a lawyer, would be the first Hispanic-American to become the country's top law-enforcement official.
But his approval is not a formality. Gonzales is expected to face stiff questioning at his confirmation hearings on what role Gonzales played in writing a legal opinion that outlined rules for the treatment of prisoners in Afghanistan and Iraq.
Civil liberties groups have said this opinion contributed to the abuse of prisoners at Abu Ghraib, a charge denied by the administration.
Despite that, it's likely Mr Gonzales will eventally be approved. He is seen as a moderate Republican, acceptable to Democrats, unlike Mr Ashcroft.
After the 11 September attacks, Mr Ashcroft ordered 5,000 foreign men, most from Middle Eastern countries, to be questioned, while denying that this was a form of racial profiling.
More than 750 people, mostly Muslims, were detained for immigration violations.
He also ordered law-enforcement officers to listen in on conversations between detainees and their lawyers.
Perhaps most controversial of all, he backed a sweeping piece of legislation, known as the Patriot Act, that gave the government the power to tap phones, track internet usage and detain immigrants.
Civil liberties groups charged that Mr Ashcroft was undermining fundamental human rights: "John Ashcroft was one of the most destructive attorneys
general in the modern era. His tenure was marked by a severe erosion of Americans' constitutional liberties," said Ralph Neas of People for the American Way, a liberal lobbying group.
There were other setbacks for Mr Ashcroft.
Earlier this year, a Supreme Court ruling rejected the administration's policies on fighting what it calls terrorism and a critical report by his own justice department's inspector general condemned the handling of the more than 700 detained people, some of whom had been physically abused.
Mr Ashcroft was also criticised for giving warnings that al-Qaeda planned to attack the United States. When they did not occur, he was taken to task for failing to give any details and for scaring people.
'Safer and stronger'
In his resignation letter, Mr Ashcroft defended his record saying: "For three years since the worst attack in our nation's history, and in defiance of all expectations, America has not endured another major terrorist attack... We live today in an America that is safer and stronger than ever before."
That was a sentiment echoed by the president: "John Ashcroft has worked tirelessly to help make our country safer."
Mr Ashcroft has said he will remain in office until Mr Gonzales is approved by the Senate.
But while he may bring a change in mood and tone to the Justice Department, it's unlikely that policy will differ dramatically from what happened in the first four years of the Bush administration.