asaik, the feds dont a have a proper law enforcement arm. they have plenty of people with guns and badges but they have specific regulations.
if the local popo dosnt arrest you, the feds have a hard time getting you prosecuted. the pot states are proving this out. dea can raid a shop here and there but they cant patrol the streets for simple possession.
i dont think this thing will hold up in the supreme court, but till its tested things will get weird.
in regular misdemeanor cases the local prosecutors office dosnt have to do much work on any give case. the case volume demands they keep things quick. once you introduce the burden of showing the states interest vs. documented religious practices, i doubt they can devote the resources to make it worth while.
in this county simple possession of pot gets you 8 days in county jail, the trial is quick, people take the days instead of risking a trial for more. now you know you have a leg to stand on and you have decent shot of a jury letting you walk. prosecutors cant afford to loose easy cases or waste the money and time. its not like we are rolling in money for frivolous persecutions.
2 miles away across the river in bhu-land, i think simple possession is a 100$ fine
and im not sure its arrestable by its self. the counties make more money off a speeding ticket than possession.