Brandishing the U.S. Constitution did not save 2 Chains and his entourage last week when cops pulled them over for a busted taillight.

As previously reported, there was a standoff between cops and 2 Chains-plus-crew on the morning of August 22 in Oklahoma.

When cops approached the tour bus, they smelled weed and saw smoke. They wanted in, but those aboard locked the doors and refused.

Apparently, one of the bus' passengers actually held a physical copy of the U.S. Constitution against the bus window ... "as if challenging officers" with his civil rights, according to a police statement.

Eventually, the bus was towed to a police training facility with the people still inside and cops gained entry, immediately arresting all passengers including 2 Chains.

Nice try guys, but weed’s not legal yet.