Old-school drug warrior Jeff Sessions ticked off 2018 with aplomb Thursday when he revoked Obama-era memos protecting state experimentation with legal weed. Federal prosecutors across the country now have more discretion to go after people who might be obeying local medical and recreational pot laws, which govern more than half the states in America. This is bad news for people who own pot businesses, the banks and financiers tempted to do business with them, and, to a lesser extent, individual pot users.

This Hamlet Act is at least a step up from President Obama’s dismissal of legalization advocacy as deeply unserious. Even as Obama moved from punitive crackdowns on pot growers in his first term to an uneasy peace in the second, in a 2015 VICE News interview , he warned young people, “You should be thinking about climate change, the economy, jobs, war and peace. Maybe, way at the bottom, you should be thinking about marijuana.”

Too many Democrats, particularly the congressional leadership, have been weirdly passive in their reaction, grumbling that Sessions should put more effort and resources into other criminal prosecutions, while refusing to commit to fixing the problem legislatively. Lawmakers seem most angry about Sessions forcing them to have to take a stand on marijuana policy, instead of relying on a fragile non-prosecution agreement.

In other words, you can only legalize marijuana by actually legalizing marijuana, permanently, at the federal level. Which is to say Democrats should stop being so characteristically flimsy—and take full advantage of the Trump administration's potentially catastrophic political mistake—by vowing to legalize marijuana if and when they get back into power.

Sessions’s statement formalizing a version of a long-feared pot crackdown put the onus on lawmakers, however, citing “Congress’ determination that marijuana is a dangerous drug and that marijuana activity is a serious crime.” On that point, he’s actually totally correct. Pot is still officially a dangerous drug, on par with heroin , under the Controlled Substances Act. The Obama-era memos were always vulnerable to the whims of a future attorney general; they were never a solution for the war on drugs.

It’s easy for Democrats to make the cold political calculation that legalization is incredibly popular , especially among infrequent voters whose turnout is needed to take back Congress. But there’s a more elemental question here: What is an opposition party for other than drawing distinctions between its agenda and that of the party in power? Legalization is one of the least-polarizing issues out there—even Republican voters give it majority support in some national surveys.

Not only was this condescension unnecessary, it was wrong. Legalization is a public health issue—locking up people for nonviolent drug offenses is unconscionable, and there is lots of evidence that the pain-relief properties of marijuana can reduce the deadly reliance on opioids, the deadliest drug epidemic in US history. It’s a racial justice issue, given the disproportionate number of minorities arrested and imprisoned for marijuana use and possession. It’s a foreign policy issue—America spends unbelievable resources battling Latin American drug gangs, whose revenue would likely dry up under a legal regime. It’s increasingly a revenue-gainer for states. And passing laws that keep marijuana a small-craft business while preventing consolidation could make it a model for an economy where gains are broadly shared, a welcome contrast in an era of seemingly relentless march toward monopoly.

Nobody has to reinvent the wheel here: there’s already legislation in Congress, with bipartisan support, that would make Sessions's decision irrelevant. Senator Cory Booker’s Marijuana Justice Act would remove pot from the list of controlled substances and expunge all marijuana-related federal convictions. There are two House versions of the bill: the Ending Federal Marijuana Prohibition Act, with 15 co-sponsors, five of them Republicans, and the Regulate Marijuana Like Alcohol Act (17 co-sponsors), which would let the Food and Drug Administration test pot for safety. A softer version, the Respect State Marijuana Laws Act, would exempt Controlled Substances Act regulation in any state where marijuana is legal. That has 24 co-sponsors, 12 Democrats and 12 Republicans. A bipartisan Congressional Cannabis Caucus could lead on any of these bills.

Even something as simple as the SAFE Banking Act would allow marijuana businesses to get a checking account and swipe debit cards without financial institutions who work with them fearing prosecution. This bid to end the incredibly unnecessary danger of all-cash marijuana businesses at risk of criminal targeting has 58 co-sponsors in the House.

So Democrats don’t even have to write new policy to meet the wishes of the public; they just have to support what already exists. To do that, though, they’ll need to understand the role of a political party in a democracy: identify ways to improve people’s lives, and then to actually commit to enacting them. If Democrats finally figure this out and support marijuana legalization, Republicans will have a choice, too: stick with Trump and Sessions and face the ire of the electorate, or join Democrats, at which point the public wins. Some Republicans, like Senator Cory Gardner of Colorado, are already rejecting Sessions's action; the issue has the potential to split the right.

It's not like some Democrats haven't been boldly fighting for legalization for some time. But the rest need to get over the party’s residual drug-warrior past and unite on a public-policy priority that would stabilize communities and save lives. Jeff Sessions does not actually have the power to dictate federal marijuana policy; Congress does. Democrats have to recognize that, and vow to do something revolutionary: use their own power.