That depends on the location. I think that in the USA people are still being locked up for marijuana use, although I guess that trend is thankfully going down. Can anyone confirm that?

Here where I live, in Brazil, you will get a lot of hassle if you're caught for marijuana possession. If you're black or poor, you're probably going to get a lot more hassle (being beaten up and being locked up for some time are almost certain to happen).

Generally, you can get away with 10 grams or something like that, but not without hassle. You better pray to Jah to not get caught :)