The focus of Ashcroft's legacy is the USA PATRIOT Act, a law passed only six weeks after the 11 September attacks. The measure -- which stands for Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism -- gave law-enforcement authorities broad new tools to avert potential threats to the United States.
Despite these enhanced powers, Ashcroft was back before Congress less than two months after that law was enacted, seeking even greater powers. In a hearing on 6 December 2001, he spoke with characteristic conviction about what he called the need to act forcefully against groups such as Al-Qaeda.
"One option is to call 11 September a fluke, to believe it could never happen again, and to live in a dream world that requires us to do nothing differently," Ashcroft said. "The other option is to fight back, to summon all our strength and all of our resources and devote ourselves to better ways to identify, disrupt, and dismantle terrorist networks."
Ashcroft's supporters speak with similar conviction about his efforts to protect the country. One of them is Trent England, a legal policy analyst at the Heritage Foundation, a private research center in Washington.
England told RFE/RL that Ashcroft's approach has been good for the simple reason that it has worked: "There's a lot of people trying to keep America safe, but John Ashcroft has certainly been one of the leaders there. We can all think back to the wake of [11 September]. I don't think that there were that many of us who really thought that we would go for 3 1/2 years after 11 September  without another major terrorist attack. And the fact that we have [gone without a terrorist attack] shows that the Justice Department has been effective."
But Ashcroft's critics say his office has created an atmosphere of intolerance against Arabs and Muslims in the United States by paying so much attention to their activities as part of the war on terrorism.
England said the facts show this not to be the case: "I think that when you look at the response of the government to the 11 September attacks, you see an incredible amount of sensitivity to the concerns of Arab-Americans. Only in America, in the wake of something like 11 September, do you see the kind of really extreme sensitivity to make sure that, not only within the government but within the population as a whole, that people were not using those attacks as some kind of an excuse for racism."
England said Ashcroft's critics are merely trying to exaggerate the attorney general's political ardor in an effort to raise money for their own operations.
In fact, England said, Ashcroft has often set aside ideology to enforce the law fairly, as when he avidly pursued people suspected of mounting attacks on abortion clinics, even though Ashcroft is a devout opponent of abortion.
James Ross took a far different view. Ross, the senior legal adviser to the advocacy group Human Rights Watch in New York, said Ashcroft's tenure has represented a step backward, not forward, for civil liberties in the United States.
Ross said many restrictive elements of the USA PATRIOT Act should be revised. Of particular concern, he said, are memos from Ashcroft's office suggesting how forceful U.S. interrogators may be in questioning prisoners being held in Iraq and at Guantanamo Bay, Cuba.
"Certainly, the role of the Justice Department in addressing such issues as torture is a real stain on the U.S. record. Where in the past the U.S. has been a leader in promoting respect for international law, [Ashcroft's] legacy and that of the administration may really be a real reversal," Ross said.
But Ashcroft's departure might offer no relief for civil libertarians. Yesterday Bush nominated his White House counsel Alberto Gonzales to succeed Ashcroft as attorney general. Gonzales was closely involved in helping draw up the rules for the Guantanamo Bay legal proceedings -- called "military commissions" -- for combatants captured in Afghanistan.
"Gonzales clearly had a clear role in instituting the military commissions," Ross said. "What [administration officials] did was basically scrap the Uniform Code of Military Justice -- the court-martial system -- and replace it with a system that doesn't recognize the [defendants'] most fundamental rights."
Those rights include those guaranteed under the Geneva Conventions. The Bush administration says the Geneva Conventions do not apply because the prisoners violated the international rules of war.
A U.S. federal court has stepped in on the first of these proceedings. It ruled that the commission prosecuting Osama bin Laden's driver, Salim Ahmed Hamdan, be halted so the defendant can have a hearing to determine whether he is a prisoner of war and therefore enjoys the protections of the Geneva Conventions.