We have a 5 cent per bag law in effect in our county (Montgomery County, MD right outside of Washington, DC). It is a real pain. We need to take our own bags to ALL stores (grocery stores, department stores, CVS, etc). It is awful when you hop into Sears for one or two items and wind up finding a bunch more...but you didn't bring enough bags inside with you. The law has made a huge difference in the number of people who are bringing re-usable bags with them, but they are also finding that there are huge losses in theft. It is very difficult to determine if someone has already paid for an item if they have already placed it in a bag that they brought...especially as you move from store to store in the mall.
Also, it is actually very unhygienic using the re-usable bags for groceries. If you buy chicken and it leaks, there is a salmonella risk...not to mention you will just want to throw out the bag because of the smell.
Suzi