The brief (courtesy of John Kruzel) makes two arguments:
First, the decision violates federal law, which establishes “the Tuesday next after the 1st Monday in November” as a single Federal Election Day, which falls on November 3rd this year. 2 U.S.C. § 7; see also 2 U.S.C. § 1; 3 U.S.C. § 1. These provisions mandate holding all elections for Congress and the Presidency on a single day throughout the Union. However, Footnote 26 and page 63 of this Court’s Slip Opinion extend Election Day past November 3, 2020. It does this by forcing election officials to accept ballots received after election day even if these ballots lack a legible postmark. This permits ballots to be both voted and counted after election day, extending the General Election past November 3, 2020. This clearly violates 2 U.S.C. § 7….
Second, the decision violates the Elections Clause, Article I, § 4 cl. 1 of the United States Constitution, by seizing control of setting the times, places, and manner of federal elections from the state legislature. Although this Court has the final say on the substantive law of Pennsylvania, the Elections Clause of the United States Constitution vests the authority to regulate the times, places, and manner, of federal elections to Pennsylvania’s General Assembly, subject only to alteration by Congress, not this Court. U.S. Const. Art. I, § 4. The General Assembly has not delegated authority to alter these regulations to the Pennsylvania Judiciary, yet this Court’s decision fundamentally changes the policy decisions inherent in the General Assembly’s duly enacted election laws. This Court has substituted its will for the will of the General Assembly and this substitution usurps the authority vested in the General Assembly by the Elections Clause. U.S. Const. Art. I, § 4.
Kruzel in The Hill:
Republicans plan to ask the Supreme Court to review a major Pennsylvania state court ruling that extended the due date for mail ballots in the key battleground state, teeing up the first test for the Supreme Court since the death of its liberal leader Justice Ruth Bader Ginsburg.
The development comes after the Pennsylvania Supreme Court dealt Republicans a major blow last week in a bitterly partisan election lawsuit that could help determine whether President Trump or Democratic nominee Joe Biden takes the Keystone State, which Trump won in 2016 by just over 44,000 votes.
The expected petition to the Supreme Court comes just days after Ginsburg’s death from cancer last Friday injected further uncertainty into a chaotic 2020 presidential contest that is on track to be the most intensely litigated election cycle in U.S. history.
“This could be a big first test for the post-RBG Supreme Court and where it will stand on election issues,” said Rick Hasen, an election law expert and law professor at the University of California Irvine. “There’s little reason to believe that the conservative-liberal divide will disappear with Justice Ginsburg’s death.”
Update: Here is a brief of the Republican Party of Pa. seeking a stay.