The collapse in Detroit of the Justice Department's first post-Sept. 11 prosecution of an alleged terrorist sleeper cell has left the Bush administration with few high-profile major criminal victories in the War on Terror (search) -- and a growing list of losses and questionable cases.

Justice Department (searchofficials insist their record since the 2001 attacks reflects a successful strategy of catching suspected terrorists long before they can launch deadly plots, even if that involves charging them with lesser crimes. Yet some legal experts and Bush administration critics say many such cases are pumped up by overzealous prosecutors.

"There's been a tendency of the Justice Department to act overly aggressively, to hold news conferences, to seek headlines, but when the facts come out they are often shown to be exaggerated," said David Cole, a Georgetown University law professor and frequent critic of Bush administration counterterrorism policies.

According to the latest available figures, the Justice Department since Sept. 11, 2001 has charged more than 310 people in terrorism-related cases and won 179 convictions -- many for such relatively minor infractions as document and credit card fraud and immigration violations.

With fighting terrorism a cornerstone of President Bush's re-election campaign, the Bush administration has been unapologetic in its aggressive approach. Attorney General John Ashcroft (search) has repeatedly said the best evidence that the strategy works is that no terror attacks on U.S. soil have occurred since Sept. 11.

"You have to have a zero-tolerance policy for anything that could germinate into a terrorist plot or facilitate a terrorist plot," said U.S. Attorney David Kelley of New York. "We've been rooting out people before things get too far along. Our success in that area has likely led to some disruption activity."

In the Detroit case, the Justice Department agreed last week with defense lawyers that charges of material support for terrorism should be dropped against two men who were convicted in the first major terrorism prosecution after the attacks. A lengthy internal probe uncovered prosecutorial misconduct that included withholding evidence that tended to bolster the men's claims of innocence.

Problems have recently cropped up in a number of other high-profile cases:

--In Portland, Ore., lawyer Brandon Mayfield was held for days as a material witness in May after the FBI (search) mistakenly said his fingerprint matched one found on a plastic bag connected to the deadly terror bombings in Madrid, Spain. Closer inspection proved the supposed match wrong.

--Two leaders of a mosque in Albany, N.Y., were released on bail Aug. 25 after a federal judge concluded the men were not as dangerous as prosecutors alleged. The evidence included a notebook found at an Iraqi terrorist camp that investigators initially said referred to one man as "commander;" FBI translators later said the reference probably means "brother."

--A Saudi college student in Boise, Idaho, was acquitted in June on charges of giving terrorists material support by creating an Internet network that prosecutors claimed fostered Islamic extremism and helped them recruit. "There was no clear-cut evidence that said he was a terrorist, so it was all on inference," juror John Steger said after the verdict.

In addition to those cases, the only person charged in the United States in the Sept. 11 attacks, Zacarias Moussaoui (search), has continued to knot up the court system by insisting on access to captured Al Qaeda (searchleaders he says can prove his innocence. His case is on hold pending resolution of that question.

And one of two U.S. citizens whom Bush declared an enemy combatant -- Yaser Esam Hamdi (search) -- is about to be returned home to Saudi Arabia in a deal being negotiated by his defense lawyer and the government. Officials say Hamdi's use as a source of intelligence has been exhausted.

The other such person, Jose Padilla (search), was arrested with great fanfare in an alleged plot to detonate a radioactive "dirty bomb" (search) in the United States. The government now says he actually intended to fill apartments with natural gas and blow them up, and it's unclear if the government will charge Padilla with a crime.

Among the main domestic successes claimed by the government:

--Guilty pleas by six Yemeni-American men in Lackawanna, N.Y., (search) on charges stemming from their attendance at Al Qaeda training camps;

--Guilty pleas from a group of Muslims in Portland, Ore., who sought to join Afghanistan's Taliban (search) in fighting U.S. forces

--Conviction of attempted airline "shoe bomber" Richard Reid (search).

Kelley, the federal prosecutor, said authorities cannot afford to wait until people with shadowy ties to terrorists move into the overt phase of launching an attack.

"If we had a really bona fide terrorist, it might be somebody who had just pulled a trigger and you'd have thousands of people dead," he said.