You can’t take marijuana across state lines. Even when two legal states share a border, as Washington and Oregon do, carrying weed across state lines runs afoul of federal law. Don’t bring it on a plane, and don’t mail it.
You can’t smoke and drive. Driving while stoned is illegal and dangerous, just like drunken driving. But there’s no Breathalyzer for weed, a conundrum for cops. That could change, because two companies out there right now- Hound Labs and Cannabix Technologies – are testing marijuana Breathalyzers.
You can’t smoke weed in public anywhere. Sorry, but those 420 pot parties in city parks are illegal, even in states where cannabis is legal.