Supreme Court justices on Wednesday expressed discomfort with giving federal district courts the power to reject updated sentencing guidelines and mitigating circumstances when considering shortening defendants' sentences.

During oral arguments in Concepcion v. United States, the justices appeared wary of siding with the U.S. government, which argues that district judges should only be required to adopt the changes to crack cocaine sentencing under the Fair Sentencing Act and be given the option to ignore factors such as good behavior and non-retroactive sentencing reforms.

That position seemed to alarm several members of the court, who appeared concerned that a ruling giving district courts wide discretion will lead to wide disparities in sentencing.

"In what world does it make sense that some district courts will take cognizance of changes in the law like that and others will not, and the results will be … dramatically different for different — individuals?" Justice Neil Gorsuch asked Assistant to the Solicitor General Matthew Guarnieri, who argued for the government. "I just don't know another area in which we give lower courts that kind of latitude."

Justice Samuel Alito appeared equally puzzled.

"Your argument introduces an enormous amount of discretion," he said. "It's hard to understand why Congress would have wanted that."

Justice Elena Kagan sounded worried that giving lower courts too much authority would also make it harder to identify judicial abuse of discretion.

The case before the court involves Carlos Concepcion, a convicted Massachusetts crack cocaine dealer who sought relief in light of reforms passed after he was sentenced to 19 years in prison in 2009. Concepcion made three unsuccessful bids to reduce his prison term after the 2010 passage of the Fair Sentencing Act, which reduced the disparity in sentences between powder and crack cocaine offenses.

In 2019, Concepcion argued that he was no longer a career offender after the passage of the First Step Act the previous year, and asked to be sentenced to time served and be released.

But a district court judge denied his motion, and the U.S. Court of Appeals for the First Circuit upheld the decision. He then petitioned the Supreme Court in May.

While the U.S. Sentencing Commission voted to apply the Fair Sentencing Act retroactively, paving the way for people sentenced before its enactment to seek a reduction in prison time, it has not done so for the First Step Act.

The First Step Act says a court "may" impose a reduced sentence, but says nothing about what factors a judge should consider when making that decision.

A circuit split emerged concerning the amount of discretion district courts can exercise when reviewing sentences under the First Step Act, such as when to consider a prisoner's rehabilitation and good conduct and possible changes in career offender status. In the First Circuit, where Concepcion's case was processed, district courts are barred from considering them. Other circuits follow both more and less restrictive standards.

On Wednesday, the Supreme Court was called to resolve the circuit split, which resulted in deeply uneven sentences across the country.

Arguing for Concepcion, Charles L. McCloud of Williams & Connolly LLP told the court that the First Circuit rule conflicts with the law's text and requires courts to ignore information that judges could use in exercising discretion in resentencing.

"The First Step Act does not require courts to ignore relevant information," he told the justices.

McCloud asked the high court to scratch the First Circuit rule and consider embracing one of two options: either rule that district courts "must consider" arguments for factual and legal developments made by the parties, or rule that the courts "may consider" those arguments.

The former will result in more consistent results in district courts, McCloud said. The latter, Concepcion's fallback position, has the endorsement of the government. Under both proposals, the district court will have a final say in determining whether a reduced sentence is appropriate for a prisoner.

Some justices struggled with the "may consider" approach.

"It sounds to me like we're delegating to — or Congress or somebody is delegating to — individual district judges the authority to determine what the law is," Chief Justice John G. Roberts Jr. said. Justice Gorsuch expressed similar doubt.

But McCloud assured the justices that the point of their ruling would be to prevent district judges from having their hands tied when confronted with factual and legal developments that would help a prisoner's case for a reduced sentence.

"Either alternative before the court today is preferable to the First Circuit's rule, and the bottom line for both is the same," McCloud said.

The only significant difference would be that under the "must consider" rule, a district court would have to redo the same analysis of factors involving a defendant's sentence — spelled out in Section 3553 (a) of Title 18 of the U.S. Code — the court does in imposing an initial sentence. Under the rule, courts would also have to consider new applicable sentencing guidelines, while they wouldn't have to with the "may consider" approach, McCloud said.

Guarnieri asked the high court to reject the "must consider" approach, arguing that the First Step Act only requires district courts to take into account the sentencing guidelines changes enacted in the Fair Sentencing Act, and nothing else. District courts, ultimately, have the power not to factor in mitigating circumstances and updated guidelines, Guarnieri said.

"It is left to the court's discretion whether to take into account these other non-retroactive guidelines," he said. "At the end of the day, these are all advisory."

That broad idea of discretion, however, troubled several members of the court.

Justice Stephen Breyer pointed out that Congress created the Sentencing Commission in the 1980s to provide sentencing ranges for district judges to consider, with the aim of reducing drastic disparities in sentencing.

"Is the [Justice] Department disowning the commission, or am I making a big mistake?" Justice Breyer said.

--Editing by Karin Roberts.