Attorney General Jeff Sessions talked a big game on marijuana, once saying that “good people don’t smoke marijuana” and indicating that the Justice Department should crack down on the drug even in states where it’s legal. But this past week, Sessions got some disappointing news for his anti-pot crusade.

On Friday, the Associated Press reported that Sessions’s Task Force on Crime Reduction and Public Safety gave him no ammo for his anti-marijuana efforts, instead only giving vague recommendations about how the attorney general should deal with marijuana in states where it’s legal. Rather than call for a sweeping crackdown, the task force said that officials “should evaluate whether to maintain, revise or rescind” Obama-era memos that let states legalize pot without too much federal interference as long as they followed certain guidelines.

Sessions doesn’t have to follow the recommendations, and his Justice Department didn’t comment to AP about the story. But the vague recommendations will put the impetus on Sessions to explain why it’s necessary to crack down on pot legalization.

This is a bit of an unusual situation: If states have decided to legalize pot on their own, why is there talk of the federal government getting involved?

In short, while states can legalize marijuana under their own laws, pot remains illegal at the federal level.

This wasn’t as much of a problem for legal pot states during the Obama years. But Sessions believes that allowing the use of any drugs, even cannabis, sends a signal across society that drug use is acceptable.

“I reject the idea that America will be a better place if marijuana is sold in every corner store. And I am astonished to hear people suggest that we can solve our heroin crisis by legalizing marijuana — so people can trade one life-wrecking dependency for another that’s only slightly less awful,” Sessions said earlier this year. “Our nation needs to say clearly once again that using drugs will destroy your life.”

Regardless of the task force’s recommendations, this sentiment is something Sessions could move on. After all, the task force still asked Sessions to “evaluate” what he wants to do with the Obama-era marijuana memos — and if his past is any indication, Sessions’s preference is a crackdown.

Sessions could use existing federal law to stifle legalization

Eight states and Washington, DC, have legalized marijuana for recreational purposes since 2012, when Colorado and Washington state became the first two to do so. But even as these states allow cannabis for recreational use, it remains illegal under federal law.

The Obama administration, through the 2013 Cole memo, told the states that as long as they follow some rules (like not letting legal pot fall into kids’ hands or flow across state borders), the feds won’t crack down. This let states carry out their legalization schemes with little federal interference — although federal law does still make it so legal pot businesses can’t claim certain tax deductions and easily access banking.

But administrations don’t have to follow the lax approach. In the past, for example, the Bush administration — and the Obama administration during its early years — cracked down on medical marijuana by raiding and shutting down pot dispensaries that were legal at the state level.

Leveraging federal law, the Drug Enforcement Administration, which falls under the Justice Department, could be freed up to raid state-legal marijuana farms and shops, confiscate these businesses’ product, and shut them down. Federal prosecutors, also under the Justice Department’s supervision, could file and prosecute federal charges against state-legal marijuana businesses, effectively treating them as illicit drug dealers.

If the Justice Department were really serious about this, it could try to shut down every state-legal marijuana business in the country. But even if the Justice Department didn’t go that far, these types of prosecutions could have a chilling effect — signaling to other states that they can’t legalize pot without risking federal enforcement, and perhaps scaring off other businesses from launching their own pot operations in states where marijuana is already legal. At the very least, aggressive action from the Justice Department could stall legalization’s progress until a new administration takes over.

Sessions could go about all of this by signing off on a new memo that simply condemns marijuana legalization. Or he could vow to really strictly enforce the Cole memo, citing federal data and news reports to argue, for example, that the states still let some legal pot go across their borders and, therefore, federal action is justified.

The question is whether he will.

Sessions has hinted he wants a crackdown, but Trump is less clear

Sessions has repeatedly suggested that he would like the Justice Department to stamp out marijuana legalization. “We need grown-ups in charge in Washington to say marijuana is not the kind of thing that ought to be legalized, it ought not to be minimized, that it's in fact a very real danger,” he said as a senator in 2016.

In July, Sessions sent a letter to Washington state officials that revealed his skepticism of legalization. “Congress has determined that marijuana is a dangerous drug and that the illegal distribution and sale of marijuana is a crime,” he wrote. “The Department remains committed to enforcing the Controlled Substances Act in a manner that efficiently applies our resources to address the most significant threats to public health and safety.”

It cited a 2016 report by the Northwest High Intensity Drug Trafficking Area, claiming that it “raises serious questions about the efficacy of marijuana ‘regulatory structures’ in your state” because, among other issues, pot remains loosely regulated and legal pot from Washington state “has been found to have been destined for 43 different states.”

As Christopher Ingraham pointed out at the Washington Post, these type of federal reports are notoriously questionable. They tend to cherry pick data, presenting a case favorable to the war on drugs and prohibition. The data from the 2016 report is also limited, covering only the first several months of Washington state allowing pot sales.

But Sessions could use these types of reports to justify his anti-marijuana crackdown. This would be part of broader “tough on crime” and anti-drug policies that he’s called for; earlier this year, for instance, he asked prosecutors to begin enforcing mandatory minimum sentences even for low-level drug offenses, rescinding a memo from the Obama administration that asked law enforcement to lay off harsh punishments for people accused of nonviolent crimes.

One big question is whether Sessions’s boss, President Donald Trump, would welcome an anti-pot crackdown. On the campaign trail, Trump said he would like to leave marijuana legalization to the states. But after Trump was elected, his press secretary told reporters, “There’s still a federal law that we need to abide by when it comes to recreational marijuana and other drugs of that nature.”

Now the eight legal pot states wait to see what the administration — and Sessions in particular — decide to do next.

For more on marijuana legalization, read Vox’s explainer.