I know all about the law. The first offense for posession under an ounce is $100 but now the city or town they catch you in can charge you an additional fine for posession or smoking in public. Springfield is $300 plus the $100 fine. South Hadley, Southampton, and Holyoke have a similiar policy but less of a fine. They don't look very far into it at all unless there is probable cause that you distribute it. Being caught with a bowl is a different story as it is considered posession of drug paraphenalia.
Hope this helped...