For drug-policy reformers, it is the best of times, it is the worst of times. Marijuana legalization seems to have hit a tipping point, and even Republicans now regard opioid addiction as a health crisis rather than a criminal one. Yet here comes Attorney General Jeff Sessions, a drug warrior from a generation ago, determined to turn back the clock.

There’s no more influential drug-policy reformer than Ethan Nadelmann, executive director of the Drug Policy Alliance, who is stepping down after leading the organization for more than 20 years. With his last day on Friday, Nadelmann sat down with The Daily Beast to reflect on his field’s remarkable past and uncertain future.

When I first met Nadelmann in the late 1990s, I thought he was nuts. The only people talking about legalizing marijuana were potheads like Cheech and Chong. But here was Nadelmann, a nerdy, wonky, Nate Silver type dissecting the “war on drugs” with cold, hard facts. I was totally convinced by his arguments, but equally convinced that they wouldn’t get anywhere.

I was wrong. Twenty years later, 60 percent of the country supports legalizing marijuana outright, up from 25 percent in the 1990s. Twenty-nine states have medical marijuana, up from zero. Eight have legalized it entirely, up from zero.