Attorney General Jeff Sessions’s tough-on-crime policies are drawing criticism from civil rights groups and lawmakers. But his efforts also face an additional, perhaps more significant roadblock: state governments. Many have taken big steps away from the incarceration-focused policies espoused by Sessions and, with the cost of imprisonment rising, cash-strapped states have a strong incentive not to reverse course.

A new report from Vera Institute of Justice highlights the efforts that states have made to reduce prison populations and cut prison costs that put a heavy burden on their budgets after the financial crisis. After years of rapid increase, the state prison population fell 5 percent from 2009 to 2015, according to the report. At least 23 states across the political spectrum have reduced their prison populations since 2010, while many others have seen only modest growth. Many states have adopted policy changes such as eliminating mandatory minimum sentences, providing alternative punishments rather than imprisonment and enhancing re-entry support to minimize recidivism.

PERCENT CHANGE FROM 2010 TO 2015 STATE PRISON POPULATION PRISON SPENDING PRISON SPENDING PER STATE RESIDENT, 2015 1 California -20.9% +7.0% $220 2 New Jersey -14.8 -10.5 152 3 South Carolina -11.9 -2.5 89 4 Connecticut -11.6 +8.2 283 5 New York -10.2 -7.6 187 6 Vermont -9.8 +2.5 186 7 Colorado -8.5 +0.0 130 8 North Carolina -7.8 -6.3 111 9 Georgia -6.3 -1.7 90 10 Massachusetts -6.2 +3.2 88 11 Rhode Island -5.0 +6.2 177 12 Maryland -4.9 -2.8 179 13 Louisiana -4.1 -6.8 133 14 Michigan -4.1 -12.4 157 15 Hawaii -3.6 +5.6 125 16 Texas -3.3 -7.4 120 17 Wisconsin -2.4 -0.1 150 18 Iowa -2.3 +4.1 100 19 Alabama -1.0 -3.4 96 20 Ohio -1.0 -12.8 115 21 Florida -0.8 -11.8 95 22 Pennsylvania -0.5 +22.3 168 23 Virginia -0.2 +3.1 98 24 Washington +1.0 -8.8 88 25 Indiana +1.1 -10.6 78 26 Delaware +1.6 +6.4 282 27 Kentucky +3.0 -4.8 79 28 South Dakota +3.0 +10.5 85 29 Arizona +4.1 +1.1 157 30 Minnesota +4.1 +3.2 74 31 Utah +5.0 +3.1 51 32 Oregon +5.2 +2.0 159 33 Oklahoma +5.7 -10.2 116 34 Illinois +5.9 +20.4 124 35 Missouri +6.1 -1.5 118 36 West Virginia +7.8 +11.0 103 37 Idaho +8.3 +18.3 109 38 Nevada +8.3 -14.7 85 39 Montana +9.2 +12.9 92 40 New Mexico +9.6 -3.8 127 41 Tennessee +9.7 +6.7 110 42 Alaska +10.1 +13.0 429 43 Kansas +11.6 +1.9 82 44 North Dakota +14.7 +6.9 87 45 Arkansas +20.2 +7.5 125 Many states have reduced their prison populations Show more rows Excludes states that didn’t respond to survey on prison costs. Figures for Alaska, Connecticut, Delaware, Hawaii, Rhode Island and Vermont include pretrial incarceration. Source: Vera Institute for Justice

Sessions is pushing in the opposite direction. In a recent memo, Sessions called for prosecutors to pursue the toughest penalties possible, including for nonviolent drug offenses that carry mandatory minimum sentences. The new policy only applies to federal prosecutors, but if Sessions really wants to change direction on criminal justice policy, he will need states’ help: State prisons and local jails account for the vast majority of U.S. incarceration, including a majority of people locked up on drug offenses. States, however, may be reluctant to follow his lead.

“The states have built up quite a strong head of steam by this point,” said Adam Gelb, director of the Public Safety Performance Project at the Pew Charitable Trusts. Gelb said states have found that the new approach works better and costs less, and he said he has seen little sign that states are reconsidering the shift since Trump took office. “We’ve had our ear to close to the ground over the past few months and haven’t picked up any signs of reform fatigue,” he said.

California, a state that has struggled with severely overcrowded prisons for decades, saw the biggest decline in prison population, 21 percent from 2010 to 2015, according to Vera’s research. New York also saw a significant decrease in prison population and spending partly because of significant changes in law enforcement practices. But the shift hasn’t been limited to blue states. South Carolina, Georgia and Texas were among the Republican-led states that cut both prison population and spending.

“What Sessions is doing is completely out of step with the bipartisan movement in the states that is predominately Republican led,” said Inimai M. Chettiar, director of the Justice Program at Brennan Center for Justice. “He’s even an outlier in his own party.”

Several different forces helped drive the bipartisan shift away from harsh sentencing, particularly for drug crimes. Liberals worried about mass incarceration’s disproportionate impact on the poor and on racial and ethnic minorities. Libertarians worried about government overreach. And policymakers across the political spectrum took note of research that found that long sentences didn’t stop drug use or prevent recidivism.

For state governments, however, the financial incentive to reduce incarceration was a particularly powerful motivator, especially after the financial crisis blew up state budgets. Vera’s analysis found that from the early 1970s to the end of 2009, state prison populations increased more than 600 percent, which had a direct influence on state budgets. In states such as Connecticut, Delaware and California, annual prison expenditures top $200 per state resident, an expensive burden that often takes away from support for other state resources. In some states, prison spending has even outpaced spending for education. Even high-incarceration states such as Louisiana and Sessions’s home state of Alabama have been looking for ways to cut spending.

South Carolina provides a particularly stark example of the pressures that states are facing, and how they are adjusting their policies to deal with them. From 1983 to 2008, the state’s corrections expenses rose by 500 percent as the prison population grew. Almost half of the state prisoners in 2009 had committed nonviolent offenses. The state projected the prison population would continue to grow, adding $141 million to the Department of Corrections’ operating cost over the next five years and an additional $317 million for construction on new facilities.

By 2010, state leaders recognized the issue and pursued comprehensive legislative reform that eliminated the mandatory minimum sentence for drug offenses and gave judges an opportunity to apply nonprison alternatives such as probation for nontrafficking drug offenses. Studies show that probation and supervision reduce recidivism by 34 percent and cost less than one-twentieth of the average cost of a day in prison. By 2015, the state had reduced the prison population by 12 percent, which was driven by a 36 percent decline in admissions for nonviolent offenses and 46 percent decrease in those admitted for parole violations. Crime rates also declined by 16 percent from 2010 to 2015, according to additional research by the Pew Charitable Trusts. Instead of the projected millions in costs, the population decline allowed the state to reduce annual spending by $11 million and the state was able to close three minimum-security prisons from 2012 to 2015.

But Vera’s research also pointed to seven states that cut spending even as their prison populations increased. For example, Nevada experienced an 8 percent increase in prison population but cut spending by 15 percent in part by cutting the number of prison employees and requiring remaining employees to take unpaid furloughs. Experts said, however that that approach can lead to fewer resources for prison facilities and can potentially impact safety of both officers and inmates.

“It’s good to reduce population and cost should come down, but if you just reduce your spending without bringing the number of prisoners down you’re exposing yourself, your state, your personnel to danger,” said Martin Horn, executive director of New York State Permanent Sentencing Commission.

Not all states have managed to cut spending. Roughly half the states in Vera’s survey increased prison spending from 2010 to 2015, and while most of the increases were small, a handful were by double-digit percentages. Personnel costs made up the bulk of prison spending and rising employment costs created pressure on some state departments. Rising health care expenses, driven in part by an aging prison population, were another big factor.

“Saving is not an automatic thing,” said Chris Mai, one of the report’s authors. “States have to make choices to make that happen. A number of states have shown that it’s possible and most of that is a result of a lower number of people in prison than before.”