EDMONTON -- Appeal Court judges in Edmonton have reserved their decision about whether Omar Khadr should serve a youth or an adult sentence for war crimes.

The former Guantanamo Bay detainee currently is serving his time as an adult in a medium-security institution in southern Alberta.

His lawyers argue that the 27-year-old should be in a provincial jail for less violent offenders because he was 15 when the crimes occurred.

The appeal judges spent much of a hearing questioning government lawyers about a decision that Khadr serve time as an adult.

The Toronto-born Khadr pleaded guilty in 2010 to five war crimes, including murder, for killing a U.S. soldier in Afghanistan.

He lost a bid last fall to be transferred to a provincial jail.

Khadr sat quietly Wednesday in a packed courtroom where 50 to 60 people listened to the arguments. An overflow courtroom was set up next door so more people could watch the proceedings on a monitor.

After Khadr pleaded guilty, a American military commission sentenced him to eight years and, in 2012, returned him to Canada. At that point, he had been detained for a decade at the U.S. military base at Guantanamo Bay in Cuba.

At issue is whether the Correctional Service of Canada has correctly interpreted the sentence. The commission -- which makes no distinction between youth and adult punishment or between consecutive and concurrent sentences -- ordered Khadr jailed for a further eight years and Canadian authorities placed him in adult custody.