More than 3,100 inmates in custody of the Bureau of Prisons were released beginning Friday as part of the Justice Department’s effort to follow a criminal justice law passed last year by Congress.

The First Step Act allows offenders to be released. Most of their convictions were drug-related crimes and they have been living in halfway houses across the United States in preparation for their release, acting BOP chief Hugh Hurwitz explained to reporters in Washington at a news conference, according to NPR.

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But not all inmates will walk free, about 900 of these inmates will be sent to detention by immigration and local authorities. The fate of their future will then be up to states or the Department of Homeland Security, Hurwitz said.

Since Donald Trump signed the law last December, the Justice Department announced 250 more inmates that are elderly or terminally ill have transitioned into home confinement or compassionate-release programs.

The First Step Act has made it easier for prisoners and their families to get advocacy access. Programs like the new law existed before but were hard to gain access to, The New York Times notes.

But government officials want to ensure this new law rolls out smoothly. “The department intends to implement this law fully and on time, with the goal of reducing crime, enhancing public safety and strengthening the rule of law,” Deputy Attorney General Jeffrey Rosen said.

A new risk assessment tool has also been unveiled by authorities designed to identify inmates that may benefit from prison programming that allows them to credits that count toward early release under the law. Under this new program, inmates will be assessed every six months.

U.S. Senators Charles Grassley (R-Iowa) and Dick Durbin (D-Ill.) said in a joint statement they would “vigilantly” look over the new assessment process.

“It’s critical that the assessment does not disproportionately designate minorities as having a higher risk of reoffending,” the senators said.

The Justice Department has also began a think tank with the Hudson Institute to assist with the assessment effort. But some Democrats don’t agree with the decision.

House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) and subcommittee chairwoman Karen Bass (D-Calif.) argued earlier this year that “The Hudson Institute and its leadership have opposed sentencing reform, opposed the First Step Act’s reforms, and authored an article entitled ‘Why Trump Should Oppose Criminal Justice Reform.'”

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They noted concern that the selection of a biased organization may result in a failed effort to diligently and effectively implement the bipartisan criminal justice reforms.

But according to CNN, the new laws efforts were highly praised on Friday by criminal justice advocates.

“This is good news and we’re happy to see that it’s starting to be implemented but we think more needs to be done and we think Congress needs to provide that oversight,” said Inimai Chettiar, policy director of the Justice Action Network.

Funding levels for the First Step Act in 2020 have not been established yet.