Greece ? Inside the gates of Athens’ main university, bonfires rage and masked gangs stockpile petroleum bombs, broken paving stones and marble hacked from the neoclassical buildings. It’s their arsenal for more possible clashes with weary police.

But a week into Greece’s worst civil unrest in decades — sparked by the police shooting of a teenage boy and then fed by anger at the country’s economic unraveling — the rioters’ best weapon is arguably the law.

They have used, some say abused, a decades-old code that bars police from university campuses. The grounds of the Athens Polytechnic have become a combination of sanctuary and makeshift armory for the bands of young men and women who have left parts of the capital ransacked and smoldering.

The image of a tank rolling crashing the Polytechnic’s gates on Nov. 17, 1973, to quell a student uprising against the military dictatorship is known to every Greek.

The university amnesty law — drafted after the restoration of democracy — is a near airtight ban against police entering university or school campuses across the country. Its stated goal was to safeguard “academic freedom” and other ideals of openness.

But for years it also has given radicals a safe haven in which to regroup, rearm and launch hit-and-run attacks during frequent protests.