This is from the arrest record apparently. Source.
According to the Ouachita Parish booking report for the two men, an officer approached their car at 2:33 a.m. Tuesday in a local park, smelling marijuana. Robinson was the driver, and the officer found the drug on his floorboard and a stolen gun under his seat, according to the report. The report says the park was closed at the time.
I believe the smell of a controlled substance and/or trespassing warrants the probable cause to search the vehicle, doesn't it?
*EDIT* SM beat me to it