First I'd like to know what the hell "brought to justice" means. It's vague, sounds like a good thing, and can't be called out as a direct lie, which is why I suppose they have told Bush to use it.
Second, here's the truth of the statement, as reported on factcheck.org.
Al Qaeda
The President said twice that "75 percent" of al Qaeda leaders have been "brought to justice." But as The Associated Press reported Oct. 1, Bush was referring to the deaths or arrests of 75 percent of bin Laden's network at the time of the September 11 attacks -- not those who are running the terrorist organization today. The AP also reported that the CIA said earlier in the year two-thirds of those leaders are gone; at his acceptance speech in September, Bush increased his count to three-fourths based on unreleased intelligence data.
Furthermore, the London-based International Institute for Strategic Studies reported May 25 that the occupation of Iraq has helped al Qaeda recruit more members. The institute quoted "conservative" intelligence estimates as saying that al Qaeda has 18,000 potential operatives and is present in more than 60 countries.
This Newsweek article further explains why this claim is simply another bunch of smoke being blown up people's arses.
Anyone want to tell me why they feel Bush hasn't misled the country again?