“The evidence indicates that the legislature enacted H.B. 176 to reduce voting by young people for perceived political benefit and that the legislature was well aware that H.B. 176 would have a disproportionate negative impact on Native American voters and young voters,” wrote Judge Moses, who was first appointed by former Gov. Steve Bullock, a Democrat.

That finding is notable because the plaintiffs had not formally made accusations of discriminatory intent, said Jacqueline de León, a lawyer at the Native American Rights Fund who represented Western Native Voice and the tribes.

Secretary of State Christi Jacobsen plans to appeal to the Montana Supreme Court, a spokesman, Richie Melby, said on Thursday.

For now, the restrictions are not in effect, and the appeals process is likely to take far more than a month. But the state could request an emergency stay to reinstate the laws for the Nov. 8 election. Mr. Melby did not respond when asked if it would seek that.

It was unlikely that the Montana Supreme Court would grant an emergency stay if asked, according to Alex Rate, the legal director for the American Civil Liberties Union of Montana, which also represented the tribes. The court previously upheld a preliminary injunction against the laws, and with so few weeks until the election, “there’s a thumb on the scale for maintaining continuity,” Mr. Rate said. “Election administrators need some certainty here.”

But unlikely is not impossible. Even now, some confusion and miscommunications have been reported. Ms. Gray said that, at a meeting on Thursday with tribal officials, a worker from the Glacier County clerk’s office had appeared unaware of the ruling and said same-day voter registration would not be available. The county clerk, Mandi Bird Kennerly, told The New York Times on Friday that this was not true and that same-day registration would be available.

The effects of Judge Moses’s ruling have begun to play out.

In past elections, Western Native Voice drove hundreds of miles back and forth between reservations and county seats, delivering ballots for people who could not make the drive themselves because of distance or illness. If the ballot collection ban were in effect, many of those people would be unable to vote.