Pennsylvania the Keystone?
Pennsylvania Democratic Party v. Boockvar
Issues: Whether a decision by the Pennsylvania Supreme Court requiring the state to count mail-in ballots received up to three days after Election Day, as long as they are not clearly postmarked after Election Day, violates federal election law and the Constitution.
https://www.supremecourt.gov/docket/docketfiles/html/public/20-542.html
Pennsylvania Democratic Party v. Boockvar
Issues: Whether a decision by the Pennsylvania Supreme Court requiring the state to count mail-in ballots received up to three days after Election Day, as long as they are not clearly postmarked after Election Day, violates federal election law and the Constitution.
https://www.supremecourt.gov/docket/docketfiles/html/public/20-542.html