If you live in Colorado or Washington, you might be forgiven for thinking marijuana reform is a thing of the past. Your state has already legalized weed, after all, and it takes nothing more complicated than a trip to the store to buy it.

Most of America’s tokers are still waiting for relief, however. If there’s hope, and there is, it’s in the sheer momentum that drives legalization movements. Once started, they’re almost impossible to stop for good.

But that raises the question: Just how inevitable is legal pot? Most people seem to think it’s a near-certainty, given recent changes in public opinion and state laws.

Are they right? Is legalization already a done deal, or could events still get in the way?

Two states, Washington and Colorado, have legalized weed for recreational purposes, while 21 others have adopted medical marijuana. Sixteen states have removed criminal penalties for possession and replaced them with civil fines.

The issue is even popping up in Congress, one of the most unlikely places imaginable for drug-policy reform. Lawmakers in the House recently passed two pro-marijuana bills, while the Senate is considering another.

Still, cannabis remains entirely illegal under the federal Controlled Substances Act, which regulates dangerous substances. Marijuana is included in schedule 1 of the act, reserved for the most dangerous, most addictive, and least medically useful drugs, including heroin, ecstasy, and peyote.

To make weed legal nationally, either Congress or the Obama administration must change that listing. And that’s the biggest potential sticking point for reform in coming years.

If cannabis advocates are going to run into a brick wall anywhere, it’s the federal government. States are increasingly willing to open the legal doors to weed, but the feds show few signs of budging.

Obama himself has said he’s amenable to relisting marijuana in conjunction with Congress. But lawmakers haven’t responded in kind. The Senate is relatively open to reform, but the House is controlled by conservative Republicans, many hostile to changes in drug policy.

Unless the GOP loses control of the House this year – an unlikely scenario – that obstacle will probably remain in place until at least 2016.

Obama could tell Attorney General Eric Holder to order the DEA to reschedule cannabis on its own. But the anti-drug agency is headed by Michele Leonhart, a fierce opponent of any pot-related reform, and she would almost certainly put up a fight.

What’s more, Obama isn’t likely to risk capital on a political issue that impacts a relatively small portion of the population. That leaves any hope for legalization in the hands of Congress.

The hurdles in Congress are big, but not so big they can’t be cleared. When enough states have legalized weed on their own, it’s likely federal lawmakers will have no choice but to turn the page on prohibition.

But inevitable? That’s another story.

legal marijuana, medical marijuana, recreational marijuana