The New Hampshire Supreme Court struck a final blow Friday to a 2017 voter registration law that faced repeated legislative and court challenges, upholding a previous ruling that it’s unconstitutional.

The law required additional documentation from voters who register within 30 days of an election. It was passed by the Republican Legislature after President Donald Trump alleged that widespread voter fraud led to his loss in the state in 2016, though there is no evidence to support that and voter fraud cases are rare. Supporters said the law would increase trust in elections by requiring people to prove they live where they vote, but opponents argued it was confusing, unnecessary and intimidating.

After the New Hampshire Democratic Party and the League of Women Voters sued, a judge allowed the law to take effect in 2018 but blocked penalties of a $5,000 fine and a year in jail for fraud. In 2019, after Democrats won control of the Legislature, lawmakers passed a bill to repeal the law, but it was vetoed by Republican Gov. Chris Sununu.

The case went to trial in late 2019, and a judge ruled in April 2020 that the law was unconstitutional. The Supreme Court upheld that decision Friday.

“We acknowledge that the interests identified by the state are important, if not vital,” Justice Patrick Donovan wrote in the unanimous order. But the law failed to further those objectives while imposing unreasonable burdens on the right to vote, the court concluded.

Democratic Party Chair Ray Buckley said the ruling “sends a clear message to Chris Sununu and NH Republicans that their insidious voter suppression schemes will not stand in New Hampshire.”

“Today, we celebrate this incredible victory for voting rights. Tomorrow, we will continue to work to protect voting rights in the Granite State,” he said in a statement.

Sununu encouraged the Legislature to propose new legislation taking the court order into account.

“It’s disappointing that these commonsense reforms were not supported by our Supreme Court, but we have to respect their decision,” he said.

In its ruling, the court rejected the state’s argument that the law could only be struck down if it was unconstitutional in every set of circumstances. Similarly, it disagreed with the state’s claim that the law shouldn’t be deemed unconstitutional because only some, but not all, voters are burdened by it.