The recount underway in Pennsylvania’s U.S. Senate race marks the end of a chaotic post-election period that has become the latest example of how disputed election rules can expose weak points in a core function of American democracy.

The ruling comes after several Philly-area counties defied the court's previous guidance. The issue has come under close scrutiny as the race between Bob Casey and Dave McCormick undergoes a recount.

"County officials in each of our 67 counties were damned if they did and damned if they didn’t – likely facing legal action no matter which decision they made on counting," Gov. Josh Shapiro said.

Gov. Josh Shapiro (D-PA) sided with the Pennsylvania Supreme Court in its ruling that faulty mail-in ballots can’t be counted. Four Pennsylvania counties openly disregarded a ruling from the highest state court that ballots without signatures or dates cannot be counted,

The Pennsylvania Supreme Court on Monday rebuked Democratic-controlled elections boards that counted undated and misdated mail ballots, siding with Republicans and reiterating that such votes are invalid.

Court's order was in response to petitions filed by Republican National Committee over attempts by some county board of elections to flout the state's election law and prior court orders. More than one thousand ballots were at stake in the offending counties.

The Pennsylvania Supreme Court has directed county officials not to count mail ballots for the general election that arrived on time but in envelopes missing the correct date handwritten by voters.

The Pennsylvania Supreme Court ruled Monday that mail-in ballots in the Nov. 5 election that lacked handwritten dates or were improperly dated on their outer envelopes as required under state law cannot be counted.