The Supreme Court on Friday handed a loss to Republicans by allowing Pennsylvania voters who sent mail-in ballots that were flagged as being potentially defective to submit a separate provisional in-person ballot.
The justices with no noted dissents rejected a Republican request to put on hold a Pennsylvania Supreme Court ruling from last week.
Justice Samuel Alito, one of the court's conservatives, wrote a brief statement saying that although it is an issue of "considerable importance" there were several reasons for the court to not get involved at this stage. His statement was joined by two other conservatives, Justice Clarence Thomas and Justice Neil Gorsuch.
The case, as Alito noted, arose from a dispute over two ballots submitted during the "long-completed" Democratic primary in Butler County this year. Although it is unclear exactly how many ballots the legal theory would affect if it applied to the general election, it could be several thousand and have major legal ramifications if any statewide contests are close in the key swing state.
Get Tri-state area news delivered to your inbox.> Sign up for NBC New York's News Headlines newsletter.
The Supreme Court action does not definitively resolve the legal issue, which could yet return to the justices.
Many of Pennsylvania's counties, which administer elections, already allowed for voters to cast provisional ballots if their mail-in ballots lacked a secrecy envelope even before the recent state Supreme Court ruling. Some do not.
More litigation is possible in the coming days.
The state court had concluded that mail-in ballots that machines detect as lacking secondary “secrecy envelopes” required under Pennsylvania law are void, therefore allowing the voter to cast a provisional ballot, a finding that Republicans had argued against.
Such ballots automatically lead to voters being notified that there are problems with the ballots that can be remedied by voting in person.
In their filing at the Supreme Court, Republicans said that state law requires any ballots that do not meet the strict standards to be rejected and does not allow for voters to get a do-over. Under their interpretation of the law, that would include not just ballots lacking the secrecy sleeve, but also ballots that are not dated, not dated correctly or lack a signature.
The state, which was not sued and is not a defendant in the case, filed a friend-of-the-court brief at the Supreme Court urging the justices not to intervene, saying the ruling from the top state court did not institute a dramatic change.
Lawyers for the state wrote that Supreme Court intervention would only serve to prevent two votes in the Democratic primary from being counted months after the fact.
The litigation raises a legal question of interest to conservatives on the Supreme Court about whether the ruling from Pennsylvania's high court unlawfully encroaches on the Legislature’s authority to set election rules under the U.S. Constitution.
The issue was the subject of a Supreme Court ruling last year that largely rejected the “independent state legislature” theory, which says legislatures have unfettered authority over elections, while leaving the door open to revisit the matter in future.
Republicans in the 2020 election repeatedly argued that Democratic officials and state courts inappropriately changed election rules, mostly to address health concerns raised by the Covid pandemic. Those cases provided fodder for then-President Donald Trump’s failed efforts to overturn his election loss. Trump in 2020 also frequently railed against the expanded use of mail-in voting.
The latest case arose when two Butler County voters, Faith Genser and Frank Matis, sent defective mail-in ballots in the primary election and were notified they would not be counted. They subsequently cast provisional ballots in person.
They filed a lawsuit after being told that the votes would not be counted. The Republican National Committee then intervened.
Genser and Matis lost in a trial court, but an intermediate appeals court and the Pennsylvania Supreme Court ruled in their favor, prompting Republicans to appeal again to the U.S. Supreme Court.
The Republican National Committee and affiliated lawyers have filed a slew of lawsuits ahead of the 2024 general election in swing states, including Pennsylvania, with Trump among those fueling unfounded concerns of widespread election fraud.
In 2020, President Joe Biden won Pennsylvania by just over 80,000 votes.
This story first appeared on NBCNews.com. More from NBC News: