Attorney General Jeff Sessions doesn’t seem to grasp a basic fact about the war on drugs – it didn’t work.

Three decades of aggressive policing and harsh sentencing for low-level drug offenders clogged our prisons and disrupted the lives of millions of Americans, all while failing to reverse a growing drug epidemic that continues to ravage communities across our country.

So, why does the attorney general insist on refighting a battle we already lost? Because he doesn’t understand the problem. Sessions clings to the misguided belief that we can tackle crime – and our drug epidemic – by locking more people up and saddling them with longer prison sentences.

His tough-on-crime rhetoric ignores a growing body of research that shows there is absolutely no link between incarceration rates and the prevalence of drug use. Just this week, the Pew Charitable Trusts confirmed that view in a letter to President Trump’s Commission on Combating Drug Addiction and the Opioid Crisis.

If anything, research suggests drug-treatment facilities and other prison alternatives are more effective at curbing drug use and preventing future crime, while costing taxpayers far less than warehousing low-level drug offenders. Because Congress has fallen short in its efforts to reform our criminal-justice system, states offer the most compelling evidence for how these reforms save money and make our communities safer.

Michigan aggressively prosecuted drug crimes before updating its mandatory minimum sentencing laws more than a decade ago. The reforms included heavy investments in drug courts that have since become a model for other states. The results are a testament to effectiveness of these policies. The share of drug offenders who wind up in prison fell from 20 percent in 1998 to 12 percent in 2015. Violent crime dropped 25 percent between 2000 and 2015 and property crime was nearly cut in half.

Over the last decade, dozens of states across the political spectrum adopted criminal justice reforms to reduce their prison populations and help people re-enter society when their sentence ends, policies that made those communities safer. Between 2010 and 2015, crime rates fell further in the 10 states with the biggest decline in their prison populations than the 10 states with the fastest prison growth, according to the Pew Charitable Trusts.

Those results upend Sessions’ misguided claims that more practical prosecution guidelines for drug cases fueled a recent uptick in violent crime. In fact, data shows longer prison sentences do not result in lower crime rates. As evidence, people sentenced to 10 or more years in prison were just as likely to be re-arrested as those sentenced between two and four years.

As a former U.S. attorney for Utah, I prosecuted hundreds of drug and violent crimes. The experience taught me one-size-fits-all sentencing guidelines overemphasize misleading factors, like the quantity of drugs seized during an arrest, over more important factors, like a person’s role in the drug syndicate.

Federal sentencing guidelines can be used to attach stiffer penalties to so-called drug “mules” caught transporting cocaine or heroin than the higher-level lieutenants who oversee the flow of drugs into this country, all because the mule was caught in possession of actual drugs.

By reinstating these policies, Sessions is creating the wrong incentives for federal prosecutors, encouraging them to pursue lower-level drug dealers rather than the high-value targets who are harder to catch. The system rewards quantity over quality by diverting money to the prosecutors who hit their “numbers,” not those who make an actual difference in their communities.

These longer prison sentences for low-level drug offenders are also a big reason the federal prison budget ballooned by 595 percent between 1980 and 2013. That money would be better spent prosecuting high-level traffickers.

One of the sad realities I witnessed as a federal prosecutor is that the couriers and street dealers I sent to prison were quickly replaced by new recruits. This endless pipeline drew new people into drug trade faster than law enforcement could lock them up, creating a vicious cycle that accelerated incarceration rates while making no real impact on the drug problem.

Many of the people locked up for drug crimes suffer from addiction. That is why a number of states have redirected money to drug-treatment programs and adopted other policies to address the underlying drivers of this ongoing addiction crisis.

The success of those state-level programs seems lost on the attorney general. Sessions repeatedly cites increased drug use and the 52,000 Americans who died of a drug overdose in 2015 as reasons to lock more people up. But his recent Washington Post op-ed failed to offer a single proposal to treat that addiction in the court or prison system.

Sessions argued this shift back to tough-on-crime sentencing policies would benefit “minority communities … disproportionately impacted by violent drug trafficking” and “poor neighborhoods … too often ignored in these conversations.”

His claim ignores decades of sustained advocacy by community and faith-based groups that aggressive policing and mandatory minimums drove sky-high incarceration rates that hollowed out these same poor, minority communities.

President Trump would be wise to solicit input from other experts when it comes to criminal justice reform. He would not want his legacy defined by policies that haven’t worked and stir widespread suspicion from some of the same constituencies he promised to help.

Even in some of the most conservative states we are seeing the benefits of common-sense criminal justice reforms, so it would be a shame if the president allows Sessions to reprise policies that have already failed.