Thursday is the first anniversary of Jeff Sessions’s confirmation as attorney general. Over the past year, he has announced that he would seek to increase the use of the federal death penalty; reversed a series of Obama-era memos that instructed federal prosecutors not to go after the marijuana industry in the states that have legalized it; and directed prosecutors to slap drug suspects with the most serious charge they can prove.

None of these policies would have seemed out of place 30 years ago. And, in fact, it’s clear that Sessions has set his sights on returning the country’s criminal justice system to the days of harsh penalties for crime and hardline drug laws. The problem: A lot has changed over the last three decades — in particular, crime and our understanding of how to fight it.

Thirty years ago, there were open-air drug markets in big cities from New York to Los Angeles, residents of those cities were robbed or even killed on public transportation, and the murder rate was near its all-time high. At the crest of the crime wave, harsher penalties for criminals like mandatory minimum sentences and expanded use of the death penalty seemed like a reasonable response to a devastating national crisis, and most Americans supported them.

But today, the crime rate is much lower than in the 1990s, and Sessions’s policies are out of step with most public opinion. Moreover, many criminologists view his strategy as a throwback that’s unlikely to significantly curb violence or drug crime.

That’s because since these policies were implemented, decades of social science research has led experts like David Kennedy, a professor of criminal justice at the John Jay College of Criminal Justice in New York City, to conclude that they don’t work well enough to justify their cost. “The evidence shows that they’re expensive, there’s enormous human damage, and they’re not actually effective in deterring crime,” he said.

Sessions has long established himself as a hard-liner on criminal justice issues: As Alabama’s attorney general, he proposed a crime bill that would have made the death penalty mandatory for a second conviction for drug trafficking. As the U.S. attorney general, he’s billed his new policies as a rejection of the “soft” strategies on crime that characterized the Obama administration, arguing that capital punishment and long sentences deter criminals and that pot is a “gateway drug” for harder substances and addiction.

There’s no question that crime did start to drop precipitously during the era of harsher penalties. And in 2010, the homicide rate hit a four-decade low, according to the Bureau of Justice Statistics. Though most experts agree that the harsher strategies alone can’t explain the decline, there’s still no consensus about why the crime rate started to drop three decades ago. Scholars do note that it was already falling before many tough-on-crime measures were widely introduced, and they have offered theories from improved policing to the roaring economic growth of the 1990s to explain the change.

Richard Rosenfeld, a criminologist at the University of Missouri-St. Louis, said Sessions deserves some credit for calling attention to the recent uptick in the murder rate, which rose for the second consecutive year in 2016 after a 25-year decline.

But Rosenfeld, who studies the causes behind crime rate shifts, and other mainstream criminal justice experts reject the notion that the Obama-era criminal justice reforms, like the decision not to pursue mandatory minimum sentences for low-level drug offenders, caused an increase in violent crime. Instead, Rosenfeld blames the increased violence in part on the drug market, with more demand for heroin because of the opioid epidemic. Rosenfeld also said that tensions between African-American communities and the police could be a factor.

And there’s even debate about whether the violent crime rate — as opposed to just the murder rate — is actually increasing. With a criminal justice outlook that seems more suited to the 1990s than today, Sessions finds himself implementing policies on sentencing, capital punishment and drug enforcement — particularly marijuana — that are out of sync with much of the country.

Prison sentences

Americans today show much less appetite for tough-on-crime approaches than they did in 1992, when 83 percent of respondents in a Gallup poll said that the country’s criminal justice system was not tough enough, while 12 percent said it was about right and only 2 percent said it was too tough.

Two years later, Congress passed a crime bill imposing tougher sentences and “three strikes” provisions that significantly increased sentences for people with two or more prior convictions. It built on a 1986 law that established the first federal mandatory minimum sentences triggered by specific amounts of cocaine. With sentences increased and no possibility of parole in the federal system for those who committed offenses after 1987, the federal prison population skyrocketed in the 1980s and 1990s, driven by longer stays for drug offenders. Roughly half of federal prisoners today are behind bars for drug crimes, and their average time served more than doubled between 1988 and 2012.

Today many Americans think the criminal system is tough enough — and that previous crime legislation may have gone too far. Gallup asked the “tough on crime” question in a handful of later polls and found that the percentage of Americans who said the criminal justice system was not tough enough had declined precipitously, although a plurality (45 percent) still thought it was not sufficiently tough. Part of the explanation may be that the opioid crisis has changed the way some Americans think about responses to drug abuse. But others speculate that Americans think the pendulum has swung too far — whether because of the expense of mass incarceration or its disproportionate effects on African-American men — and there’s now broad-based support for the reforms that Sessions dislikes. Recent polls have shown that 61 percent of Americans believe prisons hold too many drug offenders, 77 percent support ending mandatory minimum sentences, and at least 83 percent favor reforms that reduce prison sentences in some cases.

Shrinking support for a ‘tough on crime’ justice system Share of respondents who think the criminal justice system is too tough, not tough enough or about right in its handling of crime, 1992-2016 1992 2000 2003 2016 Too tough 2% 3% 6% 14% Not tough enough 83 70 65 45 About right 12 22 26 35 No opinion 3 5 3 6 Source: Gallup

Research largely backs up this rejection of “tough on crime” sentencing policies. First, there’s the fact that most violent crime is handled at the state level, so federal policy has a fairly minimal effect on curbing it. “What happens at the national level gets a lot of attention, but it doesn’t have much of an impact on violent crime,” Kennedy said.

A 2014 National Academy of Sciences study concluded that the effect of mass incarceration on reducing crime was “unlikely to have been large.” That’s because long sentences are not a very good deterrent for crime, nor are they a particularly efficient way to incapacitate people who are threats to public safety.

Studies have shown that the certainty of being caught is far more important as a deterrent than the length of the sentence. And prison sentences in the U.S. are already so long, Kennedy said, that the possibility of spending an additional 10 or 20 years in prison just doesn’t matter to people who commit crimes — if they’re even aware of how the byzantine federal sentencing guidelines would affect them.

Some research suggests that longer stints in prison can actually result in more crime by encouraging the formation of criminal networks behind bars. The lack of economic opportunity for ex-felons can also prompt recidivism — that’s why a 2016 report by the Brennan Center for Justice recommended incarcerating fewer people and for shorter periods of time.

From a public safety perspective, the value of incarcerating people for violent crime diminishes rapidly as well because these crimes tend to be committed by young people. “Violent offenders tend to stop by the age of 30,” Kennedy said. “So if you send someone to prison at the age of 24 and they serve a 20-year sentence, that’s essentially 16 years of meaningless incarceration.”

Death penalty

The 1990s also saw a surge in the use of capital punishment. The Supreme Court lifted a death penalty moratorium in 1976, leading to the resumption of executions in 1977 after a 10-year hiatus. As death penalty cases restarted in the early 1980s and the death row population swelled, the number of state, military and federal executions snowballed, reaching a post-1976 peak of 98 in 1999. Since then, death penalty cases have fallen, with prosecutors less likely to ask for the death penalty and juries less willing to hand down death sentences.

Also since the mid-’90s, public support for capital punishment has fallen substantially. According to a Gallup poll conducted in 2017, 55 percent of Americans favor the death penalty for a person convicted of murder, down from 80 percent in 1994 and the lowest level of support in more than 40 years.

This seems to be due to a few factors, including the drop in the crime rate, concerns about the cost of the legal battles that precede an execution and high-profile exonerations of prisoners who had already been executed or were on death row.

Meanwhile, Sessions’s claim that capital punishment is a “valuable tool in the belt” doesn’t hold up to scientific scrutiny. Daniel Nagin, a criminologist at Carnegie Mellon University, chaired a National Academy of Sciences panel on the deterrent effects of the death penalty and found that the available evidence is “so badly flawed that it doesn’t tell us anything about whether capital punishment increases homicide, decreases it or has no effect.”

Part of the problem, Nagin said, is that it’s extremely difficult to measure people’s perception of the risk that they could receive the death penalty since it’s only carried out regularly in a handful of states. This problem is compounded on the federal level because many people may not be aware of which crimes are federal and punishable by death.

Drug enforcement

Legal marijuana has been another long-time bugbear for Sessions, and that’s also a place where the country has left him behind. At a Senate hearing on drug use in April 2016, he decried pot as “a very real danger,” adding that legislators needed “to send that message with clarity that good people don’t smoke marijuana.”

Yet states have increasingly liberalized their marijuana laws. Medical marijuana is legal for at least some diseases in 29 states, the District of Columbia, Guam and Puerto Rico, and nine states have legalized both medical and recreational marijuana use.

Marijuana is still illegal on the federal level, though, and earlier this year, Sessions revoked an Obama-era policy directive that had discouraged federal prosecutors from enforcing the law in the states where marijuana is legal. The move opens the door to a federal crackdown on marijuana growers and sellers across the country in an industry that has burgeoned quickly in part because of the lack of federal enforcement.

But public support for legal marijuana — for both medicinal and recreational uses — has ballooned over the past decade, driven partially by the marijuana industry’s success in the states that have legalized it. Sessions is even at odds with members of his own party on this issue, setting up a potential collision course with Congress if federal prosecutors begin clamping down on legal pot.

And it’s not clear that tougher enforcement of drug laws — whether it’s cracking down on legal marijuana or stepping up other drug prosecutions — will result in reduced crime. In fact, studies have shown that increasing illegal drug enforcement could result in more violence.

Efforts to figure out whether legal marijuana causes crime, either between states or around dispensaries, have been inconclusive, according to Rosanna Smart, an economist at the RAND Corp. But one recent study suggests that the availability of legal medical marijuana may be reducing violent crime along the U.S.-Mexico border by creating less demand for black-market pot.

It’s unlikely that these criticisms will deter Sessions, who is so enthusiastic about the criminal justice strategies of the 1980s and ’90s that he’s even talked about reviving D.A.R.E, an anti-drug program targeted at kids that experts now criticize. But if Sessions’s goal is to bring down crime, he’s unlikely to be successful.

“There’s no evidence that the war on drugs reduced crime,” Rosenfeld said. “We’ve learned some important lessons from those days of highly punitive responses, but now we seem to be going back in the wrong direction.”