In Washington DC it’s now legal to possess marijuana, to grow it, to smoke it and to give it away. But you’re not allowed to trade in it. You can give your neighbor up to an ounce, but if he gives you money or even bakes you a pie in exchange, that’s illegal. The District of Columbia has legalized marijuana — but is trying not to create a market in marijuana. It’s aiming for a gift economy. The district’s lawmakers aren’t happy about the process, but maybe they should be pleased about the outcome.