By Carol Rosenberg | The Miami Herald

GUANTANAMO BAY NAVY BASE, Cuba — Lawyers opened the second week of the terror trial of Osama bin Laden's driver Monday with dueling expert testimony, about the nature of war, and the nature of al Qaida.

In the morning, a former Pentagon law of war expert testified for the driver's defense team that until the Sept. 11, 2001, attacks, the U.S. war on terror was an on-again, off-again military matter and mostly a federal criminal investigation.

Before 9/11, ''We treated this enemy predominantly as a terrorist threat subject to our law enforcement response capability,'' said retired Lt. Col. Geoffrey Corn.

During those years the military's use was limited. As examples he cited the retaliatory attacks for the 1998 East Africa embassies bombings, when President Clinton ordered air strikes on a suspected al Qaeda site in Khartoum, Sudan, and training camps in Afghanistan.

Once al Qaida killed nearly 3,000 dead in the Pentagon, World Trade Center and a Pennsylvania field, ''the stakes had been raised,'' Corn testified.

And the Bush administration made an affirmative decision to employ military force, full-time. ''We recognized at that point,'' said Corn, "that the best and most effective way to respond to it was the use of combat power.''

At issue is a core of the sweeping conspiracy charge against Salim Hamdan, 37, the Yemeni driver accused of also providing material support for terror as bin Laden's $200-a-month driver.

Prosecutors claim he joined the conspiracy the first time Hamdan set foot in Afghanistan in 1996, in a failed bid to join a jihad in Tajikistan. They allege his crimes cover the era of the embassies car bombings and a suicide attack by an explosives-laden boat on the USS Cole in 2002, even though he neither plotted nor knew about the terror attacks beforehand.

Defense lawyers argue he drove for a wage, not ideology, and began around the time of the Sept. 11 attacks.

The military judge, Navy Capt. Keith Allred, has said he will include the start-of-the-war issue in his instructions to the jury of six U.S. military officers, when they decide the case.

Corn testified Monday morning through video link from Madrid, as a defense witness. Allred allowed him to go early — before the prosecution finishes its case — as a convenience, since the retired officer who now teaches law in Houston is on vacation.

In the afternoon, a counter-terrorism scholar brought a movie he made to instruct the military jury on the roots and propaganda tactics of al Qaida.

Georgetown University graduate Evan Kohlmann was expected later in the day to narrate the movie, called The al Qaida Plan, which he made at Pentagon expense for use at the first U.S. war crimes tribunal since World War II.

He modeled the video after The Nazi Plan, an instructional movie shown at the late 1940s Nuremberg tribunals for the most senior Nazi leadership.

He explained that he had been studying al Qaida since college, and spent so much time at it, "that I know the voice of Osama bin Laden now better than my family members'.''