GUANTANAMO BAY, Cuba — A new courthouse is under construction at Guantanamo Bay, a prefab tent city dubbed "Camp Justice." It's the specially designed setting for the historic war crimes trials so plagued with controversy.

"Basically the building is a big erector-set," says Maj. Chad Warren. "You just bolt it and put it together -- and you can do the exact opposite and take it down."

Canadian Omar Khadr will be the first to stand trial, a third attempt by the U.S. military to try the Toronto native on charges of murder, attempted murder, conspiracy and spying.

Khadr is one of more than 320 "enemy combatants" still held at Guantanamo Bay, the U.S. naval base in the remote southeast corner of Cuba. With no Canadian political intervention, he is the last detainee from a Western country to be held in the notorious off-shore prison.

Legal experts question the military tribunal's legal authority over captives like Khadr because he was a minor at the time of the attack. They also challenge the legitimacy of the hearings themselves. The U.S. Supreme Court has already forced Congress to revamp its military tribunal system. A system, in fact, much like the erector-set court house. Over the years, it's been bolted this way and that -- adapting and readapting to overcome legal hurdles and worldwide condemnation.

University of Toronto political scientist David Welsh says the U.S. is perpetuating fiction with the Guantanamo process, "that they are treating these people with some kind of due process."

But Welsh says there is no process. "They've been making it up as they go along," he said.

Born in Canada, Khadr returned with his family to Pakistan and then travelled to Afghanistan as a child. He was captured at 15 at a suspected al Qaeda compound, badly wounded and blinded in one eye, he was accused of throwing a grenade that killed one U.S. soldier and wounding another.

Khadr's father, Ahmed Said Khadr, was killed in 2003 in Pakistan. A military helicopter attacked a house where he was staying with senior al Qaeda operatives, and he was alleged to have been a financier for the terrorist group.

Now 21, Omar Khadr and his lawyers are challenging whether the U.S. Defence Department has the right to try him at the American naval base in Cuba.

Earlier this year, Col. Peter Brownback, who leads the military tribunal, threw out the case against Khadr, saying he did not have jurisdiction over him because he was not designated an "unlawful enemy combatant".

But a special military appeals court ruled in September that Brownback has the authority to determine whether Khadr was "unlawfully" fighting with the Taliban when the U.S. soldier, Sgt.1st Class Christopher Speer, was killed.

So Brownback's first order of business when proceedings begin Thursday will be to rule on whether Khadr was indeed an "alien unlawful enemy combatant," a ruling that is needed before the tribunal can proceed.

The prosecution is hoping to show video evidence of Khadr allegedly making bombs in Afghanistan.

It is also expected that a trial date will be set for late January 2008.