Supreme Court Photo
The U.S. Supreme Court upheld a lower court ruling preventing Arizona from denying bail to undocumented immigrants. The high court is pictured here May 18, 2015. Reuters/Joshua Roberts

The U.S. Supreme Court Monday said it agreed with a lower court’s decision to block an amendment to Arizona’s state constitution that denied bail to all undocumented immigrants charged with serious felonies. Justices refused to hear a challenge to a federal appeals court ruling that found the amendment was unconstitutional without allowing for case-by-case determinations, USA Today reported.

Arizona's initiative, approved in 2006 by 78 percent of voters, banned pretrial release for undocumented immigrants "if the proof is evident or the presumption great that the person is guilty of the offense charged." Only two other U.S. states -- Missouri and Alabama -- deny bail based on immigration status.

The Supreme Court’s most conservative judges, Justices Samuel Alito, Clarence Thomas and Antonin Scalia, said they would have agreed to hear the Arizona case. "Our indifference to cases such as this one will only embolden the lower courts to reject state laws on questionable constitutional grounds," Thomas wrote, according to USA Today.

The Supreme Court has previously ruled undocumented immigrants, who are subject to deportation and pose a flight risk, can be held without bail before a trial. Based on that 2003 ruling, three state and federal courts had allowed the Arizona amendment to continue.

An earlier case, upholding a law passed by Congress in 1984, allowed pretrial detention without bail on a case-by-case basis, especially if the individual was considered a danger to the public. That’s the precedent on which the 9th U.S. Circuit Court of Appeals relied to block Arizona’s amendment. The Supreme Court's majority Monday said it refused to second-guess the 9th Circuit.

The Supreme Court could soon take up two major cases involving undocumented immigrants. The most prominent of those cases would be a challenge to the Obama administration’s executive actions on immigration that defer deportations and extend work permits to millions of undocumented immigrants. The other case, which justices announced last week, is a challenge to voter redistricting rules that could exclude undocumented immigrants from population counts.