Welcome to the Twilight Zone, where the war on terror and the complexities of the American legal system interact.

Nothing is ever simple and straightforward in this Twilight Zone of a twilight war, because the war is like no other the United States has ever fought. The threat the American people face is all too real. Almost 3,000 Americans died in the terror attacks of Sept. 11, 2001, in no small part because the 19 al-Qaida terrorists who flew, or tried to fly, their hijacked airliners into the World Trade Center and the Pentagon -- a fourth hijacked aircraft crashed in Pennsylvania -- had been able to take advantage of American legal safeguards to organize their carnage operating freely within the United States itself.

Since that dark day, not a single al-Qaida terror attack has claimed any fatalities on the U.S. mainland. The massive tightening of national security organized by the Bush administration and pushed through with rapid and bipartisan fervor by the Republican-controlled 107th Congress has to be given at least a significant amount of credit for this usually overlooked but very real achievement.

Military policy and national security dictate ruthlessness, relentlessness and constant alertness in a war against a faceless, un-uniformed enemy that boasts of trying to gain access to nuclear, chemical and even biological weapons of mass destruction capable of killing millions of Americans.

But those dictates often clash with the demands of America's venerable and acclaimed legal system, and the results are often inconclusive and messy.

Hamdan was the first terror suspect to be held under the war on terror to be tried by a military commission. So slowly and ponderously did the Bush administration, Congress and the U.S. legal system operate that it took until now, almost seven years after Sept. 11, 2001, for the first trial under the military commission system to be held.

Hamdan was convicted on one count of providing material support for al-Qaida. But he also was acquitted on the far more serious count of being one of the inner circle around Osama bin Laden who actually planned the Sept. 11 attacks.

The trial and its outcome will please neither the right nor the left in U.S. politics. American conservatives see Hamdan as a hardened terrorist who was certainly within bin Laden's inner circle as his regular driver. Al-Qaida and its members waged war on the United States in ways not covered by the Geneva Conventions, and they committed mass murder. Hamdan is therefore not liable to any of the protections accorded to prisoners of war under the Geneva Conventions from this perspective.

However, American liberals and human rights activists around the world claim Hamdan was not granted his appropriate rights, either as an accused criminal or captured prisoner of war. He was held for well over seven years before facing trial, and the trial was by a special military tribunal. He was also, his defenders claim, physically abused while in U.S. custody.

Hamdan's trial has been compared -- sometimes unfavorably -- to the conduct of the 1946 war crimes trials of top Nazi leaders in Nuremberg, Germany, after World War II. But the cases could not be more dissimilar. Bin Laden and his inner circle completely escaped U.S.-led attempts to entrap them in Operations Anaconda and Tora Bora in Afghanistan in late 2001. Capturing Hamdan and holding him for trial is like casting a net to catch whales and landing only a sardine.

However, Hamdan's lowly status may well have been the reason he was processed first by the new U.S. military commission system. The vastly more important Khalid Sheik Mohammed, who has claimed to have been the architect of the Sept. 11 attacks, is in line to face trial soon. Trying Hamdan first gave the military commission system and its prosecutors a dry run to become familiar with the new legal process before they tackle that crucial case.

The split verdict in the Hamdan case reflects credibly on the new military commission system. Like the judges at Nuremberg, they did not come across as hanging judges, determined to convict their defendant come what may. Instead, they clearly sought to sift the evidence carefully and make necessary distinctions in assessing it. In short, they acted the way lawyers are expected to.

The Ivins case closed with far more finality and, probably, a better sense of closure for the families and other loved ones of the victims in the cases. But it left the legal outcome hanging in midair. Fort Detrick researcher Bruce Ivins last week committed suicide. The evidence carefully amassed by the FBI pointed overwhelmingly to him as the perpetrator of the anthrax attacks that paralyzed Washington shortly after the attacks of Sept. 11, 2001.

But because the defense never got its day in court, there will be no "open playing field" for the prosecution's evidence to be challenged and assessed by opposing lawyers.

This is particularly important, because over the past 12 years the American legal system and law enforcement agencies, both local and federal, have generated an appalling record of convicting suspects, later proven to be entirely innocent, by using leaks to the press that were never properly and skeptically scrutinized at the time.

Yet the outcomes of the Hamdan and Ivins cases represent probably the best that the public can hope for. The U.S. legal system and its investigative agencies reached convincing conclusions. In one case, a suspect was convicted in a court of law, and in the other, the suspect committed suicide before he could be brought to court. That is more than usually can be hoped for when a nation has to fight a war of national defense in the Twilight Zone.