The Supreme Court decided Congress didn’t mean “and” when it put that word in a 2018 federal criminal justice overhaul law that sets eligibility for a “safety valve” for defendants to avoid mandatory minimum prison sentences.

In a 6-3 decision Friday written by Justice Elena Kagan, the majority held the “and” acts more like an “or” when it comes to a three-prong test related to a defendant’s prior criminal history.

Kagan wrote that defendants would be disqualified for the safety valve if they meet any of the three criteria created by the law, rather than being disqualified only if they meet all three.

Kagan’s opinion affirmed a lower court opinion that narrowed the pathway for federal defendants to avoid mandatory minimum sentences.

The case involved an in-depth and at times philosophical analysis of what Congress meant when it wrote a particular part of the law, which focuses on severity of the “points” attributed to prior criminal history that judges are meant to use in sentencing a defendant.

The law says that defendants do not qualify for the safety valve if they have more than four criminal history points in total, an individual three-point offense “and” a two-point violent offense.

Mark Pulsifer, the federal defendant in the case, had argued that “and” meant “and” — he had a criminal history that met two of those prongs but not all three — and he should be able to reduce a 15-year mandatory minimum sentence following a 2020 guilty plea for distributing methamphetamine.

Kagan wrote that Pulsifer’s preferred reading of the law would effectively read out one of the three requirements — there is no way to have less than four criminal history points without also having a three-point criminal offense and a two-point violent offense.

Justice Neil M. Gorsuch dissented from the opinion, which was joined by Justices Sonia Sotomayor and Ketanji Brown Jackson.

Gorsuch argued the majority opinion cut against the purpose of the statute, known as the First Step Act, in which Congress meant to allow more people to avoid mandatory minimum sentences.

Gorsuch wrote the majority opinion “guarantees that thousands of people in the federal criminal justice system will be denied a chance, just a chance, at an individualized sentence.”

“It is a chance Congress promised in the First Step Act, and it is a promise this Court should have honored,” Gorsuch wrote.