Michael Mukasey emerges from the press coverage of his nomination as smarter and more thoughtful than Alberto Gonzales, more popular with Democrats, and possibly a little less dedicated to a maximalist view of the president's powers in fighting terrorism. Mukasey's closeness to Rudy Giuliani, whose main claim to the presidency is that he's a Strong Leader who will do what is necessary to defeat terrorism, is unsettling. On the brighter side, at least some defense attorneys who appeared before Mukasey when he was a federal judge describe him as fair-minded and deny that he was overly deferential to the government.
In 2002 Mukasey upheld President Bush's detention of Jose Padilla, a U.S. citizen arrested on U.S. soil, as an "enemy combatant," saying Bush was "operating at maximum authority" under the Constitution and the post-9/11 Authorization for the Use of Military Force. But he rejected the administration's contention that Padilla had no right to a lawyer and said the government had to present "some evidence to support the president's finding."
After several years in military custody, Padilla was ultimately convicted in a civilian court. In the mid-1990s Mukasey himself presided over the successful prosecution of Omar Abdel Rahman for conspiring to blow up targets in New York City. Yet he is skeptical of treating terrorists as criminals, saying trials risk exposing information useful to jihadists.
Mukasey is also described as an advocate of broad surveillance powers to prevent terrorist attacks. I'm not sure whether that means he wants Congress to grant them or thinks the president has the inherent authority to exercise them, no matter what Congress (or the courts) might say. The Padilla decision provides some hope that Mukasey would be more protective of civil liberties than Gonzales was and less inclined to support breaking the law in the name of national security—although that description also applies to John Ashcroft, which suggests how low Gonzales has set the bar.