TORONTO - Terrorism is the height of criminal behaviour — eclipsing even first-degree murder — and prison terms must reflect the severity of the offence, Crown lawyers will argue before Ontario's highest court.

The Crown is calling on the Ontario Court of Appeal to increase the sentence of Saad Khalid, a member of the so-called Toronto 18.

Khalid pleaded guilty last year to participating in a terror plot with the intention of causing an explosion. He was sentenced to 14 years, which amounts to seven more years in custody after credit for time served.

Court documents filed in advance of the hearing, scheduled for Thursday, show Crown lawyers will argue that is far too lenient for such a heinous crime.

"At present he will be eligible to walk free on parole five-and-a-half years after the date of his arrest, and be totally free of penal supervision four-and-a-half years later," the lawyers write.

"On the scale of relative severity, this crime is at the very apex, eclipsing even the most serious forms of ordinary criminal violence."

The Crown argues the starting point for sentencing for active participation in a terrorist plot intent on causing death and "indiscriminate harm" to hundreds of innocent people should be life imprisonment.

Khalid was not the leader of the plot he was convicted in, so in this case the Crown says a further four to six years should be added to Khalid's sentence, making it 18 to 20, which they had asked for at the sentencing hearing.

"The moral blameworthiness and potential impact of this crime are an order of magnitude greater than that found in a single pre-meditated homicide, for which a life sentence is automatic," the Crown writes.

"It is just and proportionate that an individual who plots a crime as this will be permanently under the supervision of the state."

The Crown also contends the trial judge erred in not making an order under the Criminal Code for terrorism offences that the offender has to serve half the sentence or 10 years, whichever is less, before being released on full parole.

Khalid's lawyers suggest in court documents that the trial judge didn't actually make any errors in sentencing, rather the Crown just didn't get their way.

"Ultimately the appellant's complaint amounts to no more than that they believe the respondent's sentence was not long enough," his lawyers write.

There were plenty of mitigating factors that justify Khalid's sentence length, his lawyers write.

He was young — 19 years old — at the time of the offence, he pleaded guilty, and he demonstrated sincere remorse, they note. A psychiatrist found he poses no acute risk to himself or others and he has sought out spiritual counselling to understand and change his thinking.

"At the time he was sentenced, he was not the same person he was when he committed the offence," his lawyers write.

He has received a great deal of support from the community, has two offers of immediate employment upon his release and 64 relatives, friends and acquaintances have contributed more than $63,000 to an educational trust fund, his lawyers say.