It’s a beautiful demonstration of how a simple piece of policy can achieve big results — while keeping everyone (except perhaps the plastic bag manufacturers) happy. Small business owners make a small additional profit, consumers learn to reuse bags, and the environment, of course, emerges the biggest winner of all.

GOOD points to a Chinese student’s research on the ban, and how it impacted consumer behavior. Here are his findings:

Consumers in Beijing and Guiyang used an average of 21 new plastic bags weekly before the bag-fee ordinance was passed in June, 2008, and rarely used the same bag twice. But after the law was imposed, consumption dropped 49 percent and nearly half of the bags were re-used. While that represents a significant reduction, researchers say there is much room for improvement, especially when it comes to enforcement. Months after the law was enacted, the researchers say, nearly 60 percent of all plastic bags were still given away free.

So the law is impressively effective even with piss-poor enforcement. I’ll turn to GOOD’s Andrew Price for the takeaway: “After its first year, The Guardian reported the ban had saved the country 40 billion plastic bags. By now the cumulative number of bags saved is probably more like 100 billion, and if the law were enforced well, it’d be a lot higher.” Yes indeed — with those kinds of results, seems it’s high time we started pushing a little harder for similar policy models (we already have some cities that charge a tax for plastic bags) here in the states.