Responding to the latest uptick in Chicago’s gun violence, President Donald Trump threatened Tuesday night to “send in the feds” if city officials fail to stop the shootings.

The provocative escalation of Trump’s law-and-order rhetoric did not come with details on what such federal intervention might look like, beyond a vague explanation from White House spokesman Sean Spicer that Trump was referring to a variety of federal “resources,” including help “through the U.S. Attorney’s office.” But an outline of the new administration’s plan for addressing what Trump has described as “American carnage” is emerging, via the confirmation process of Attorney General nominee Jeff Sessions.

Sessions’s central prescription for reducing gun violence is simple: Prosecute more firearms cases in federal courts. In testimony before the Senate Judiciary Committee and in written follow-up answers to senators, the Alabama Republican vowed to make enforcement of federal gun crimes “a top priority” and said that he expects federal gun prosecutions to increase.

“Properly enforced, federal gun laws can reduce crime in our cities and communities,” he wrote.

He also pledged to prioritize “reduction of illegal interstate trafficking of firearms.”

Sessions has joined other Republicans, conservative commentators, and gun rights groups in decrying a decline in federal gun prosecutions under former President Barack Obama. They argue that the stiffer penalties carried by federal laws pack a deterrent effect that make would-be shooters think twice before reaching for a pistol. But academic research casts doubt on those assumptions, finding no clear link between increasing federal prosecutions and decreasing homicide rates.

“I don’t think there is good evidence on the effectiveness of the kinds of things that Senator Sessions is recommending,” said Daniel Nagin, a criminologist at Carnegie Mellon University who has studied the issue.

Even more dubious to gun policy experts is Sessions’s vow to crack down on interstate trafficking. There is no federal law against gun trafficking, and as a senator, Sessions opposed legislation to create one.

Sessions has also vociferously opposed an effort by the Bureau of Alcohol, Tobacco, Firearms, and Explosives to crack down on shady gun sales by clarifying when a person is “engaged in the business of selling guns” and therefore must conduct background checks on buyers. Prior to the guidance, issued by Obama last January, the ATF complained that the rule’s lack of precision frustrated prosecutions of thousands of “unlicensed dealers masquerading as collectors or hobbyists but who are really trafficking firearms to felons or other prohibited persons.”

Additionally, Sessions indicated in his confirmation proceedings that he will not support additional funds for the ATF, which has primary responsibility for investigating gun trafficking and other significant gun crimes. The agency’s ability to police those offenses is hampered by congressional restrictions on its functions and flat budgets, according to nonpartisan analysis. A 2014 Government Accountability Office report found that the agency had about 2,600 special agents in fiscal year 2015, just 11 percent more than 2001, despite annual guns sales (as measured by background checks) more than doubling during the same period.

“With proper support and with vigorous prosecutions, ATF can be more productive without large increases in funding,” Sessions told Judiciary Committee Democrats.

How Attorneys General can influence gun prosecutions

If Sessions wants more federal gun cases, he will have the power to effect such an increase, via a policy memo to the 94 U.S. Attorneys offices around the country. Statistics maintained by the DOJ show that U.S. Attorneys have brought more gun charges when pressed to do so by past department officials. Sessions himself, while a U.S. Attorney in the Southern District of Alabama, was among the federal prosecutors to sharply increase prosecutions of gun cases during the early 1990s at the behest of then-Attorney General Richard Thornburgh, a Republican.

Federal gun prosecutions peaked in fiscal year 2005, with 13,062 defendants charged under sections of the U.S. code containing most federal gun laws, according to Justice Department statistics. The increase came in the wake of a 2004 order by then-Attorney General John Ashcroft to “pursue the most serious, readily provable offense or offenses that are supported by the facts of the case” for all federal crimes. DOJ programs to try more gun cases under the tougher federal laws, like Project Exile and its successor Project Safe Neighborhoods, also boosted federal firearms prosecutions.

As Obama’s Attorney General, Eric Holder issued a 2010 memo granting increased discretion for U.S. Attorneys. Though federal gun prosecutions had fallen below 12,000 during George W. Bush’s final year in office, critics fault the Obama administration for deprioritizing such cases. In fiscal year 2015, there were 10,564 federal gun prosecutions.

As a senator, Sessions criricized Holder’s “smart policing” policy. In his answers to the Judiciary Committee, Sessions said the greater goal should be “assurance of warranted punishment.”

Current and former federal prosecutors contacted by The Trace said that U.S. Attorneys offices could respond to the next Attorney General’s marching orders by reviewing abundant “felon-in-possession” cases, which are typically pursued by local authorities, and prosecuting enough to meet the new directive.

“They can always pump their numbers,” said Arthur Madden, a defense attorney who has practiced in the Southern District Alabama federal court since Sessions was U.S. Attorney there. “Whenever they get down, they can always make those cases.”

Critics say such practices can lead federal agents to focus finite resources on relatively low-level cases instead of bigger, time-consuming investigations.

“You’ll basically deputize [federal] agents to being super-local police,” Madden said. “States would love it because you’re shifting costs. But then who is watching Hamas and who is looking after the next Bernie Madoff prosecution? Local police can’t.”

More prosecutions may not mean less crime

Sessions has lavished praise on Project Exile, a program begun in Richmond, Virginia, in 1997 that prosecuted gun crimes using federal sentencing guidelines, and warned those convicted that they would be “exiled” to lengthy stays in faraway federal prisons. The effort, versions of which were later implemented across the country, coincided chronologically with a 31 percent drop in Richmond’s murder rate.

But studies have since cast doubt on Project Exile’s impact. In a 2003 paper, two University of Chicago professors concluded that the city’s gun violence might have fallen at about the same rate without the program; similarly sized cities enjoyed comparable declines in violence, while continuing to handle gun cases through local and state courts.

Steven Raphael, a public policy professor at the University of California at Berkeley who co-authored the study, said it is consistent with other research that has found little evidence that stiffer sentences deter crimes “that already face tough prison sentences.”

“States already prosecute felonies committed with firearms, as well as other weapons offenses,” Raphael said in an email. “It’s not clear that federalizing prosecution adds much deterrence.”

Researchers have generally found police presence in high crime areas to be a more important intervention, Raphael said.

Beyond the question of its efficacy, a key challenge for Sessions’s plans to step up gun prosecutions may be pushback from affected communities.

David Kennedy heads the National Network for Safe Communities at John Jay College of Criminal Justice. He noted that during the 1990s, fears of violent crime associated with the crack epidemic and sharp increases in homicide helped tough sentencing efforts like Project Exile win public support. But today, Kennedy said he believes Sessions faces a “quite unfavorable social setting” for the approach he appears to be preparing.

In recent years, bipartisan concern has emerged toward the mandatory sentences that have resulted in disproportionately high rates of incarceration for young black men. Sessions’s crackdown on individual illegal gun carriers would also likely come in the absence of a similar push against the traffickers who supply them, as the Attorney General nominee has given no indication that he will seek the resources and tools necessary for stanching the flow of firearms in the black market.

“Saying ‘we are going to use the power of the federal state to lock up as many young men as we can for as long as we can if they are found with a gun,’ would not go over well at all,” Kennedy predicted.