A Milan court passed a ten-year sentence on a terrorist involved in the Madrid train bombing. Why such a relatively light sentence? Because he was convicted for association with a terrorist organization rather than terrorism or conspiracy to murder.
The Milan verdict returns us to historical experience: terrorists should be tried by military tribunals, not civil courts. Tribunals curtail due process and shift the burden of proof. Enemies are presumed guilty.

To discuss bombing plots without material preparation to carry them out is no crime. Association with a terrorist organization—essentially, joining the enemy arm—is a military offense.

It is generally impossible to gather evidence for terrorist trials. Planning often takes place abroad, the immediate perpetrators die in the attack, and the sheer number of terrorists makes trials prohibitively expensive. Evidence is often gathered clandestinely, and sources cannot be revealed.

The Italian court was correct in avoiding the details. Whether the man was or was not involved in the Madrid bombings makes no difference. Rabei Ahmed was an enemy soldier and was convicted as such. The same benchmark of proof should be applied at Guantanamo.