Some cities in California either have or are contemplating banning plastic single-use bags at grocery stores (and some other venues). There has been some pushback from the plastic bag makers, pointing out that paper isn't necessarily better (anyone who has ever watched the two deteriorate in the physical environment recognizes that at least from one end of the line, this is a bullshit argument, whatever the merits might be from the other end of the line). The pushback involved a lawsuit, and so those and other cities contemplating legal action to push people from single-use to reusable bags are doing research into the impact of paper and plastic bags on the environment -- and writing rules to discourage and/or ban either, or charge for them, or whatever.
It's nice to see this progressing in the social laboratory of the Bay Area and Silicon Valley. They'll get it figured out (they're smart like that), and then we can all copy whatever they came up with, more or less the way smoking bans and other public policy initiatives worked. But I cannot help but remember that when I went to Albert Heijn shops, you just got charged a quarter euro for each bag you used. Not so much to be a problem if you needed one (and they were thick enough plastic bags that you could reuse many times, which could be handy when traveling), but enough to help you remember to bring your daypack when you went to buy groceries to make dinner for the next couple nights in the hostel. Best of all, the clerks didn't automatically grab those bags, because you bagged your own groceries, instead of fighting to get the clerk to take and use your bag and not bag your eggs and soda and whathaveyou in yet another plastic bag you were trying so hard to avoid bringing home. It's been, what, 8 years since I first encountered this strategy; I don't understand why we can't just do that.