The Constitutional Court will hear from 90 witnesses over three days to determine whether the allegations of election irregularities submitted in the Freedom Party's 150-page complaint warrant an election re-run.
Around 25 witnesses are expected to be heard today, including representatives from election authorities in South Styria, Innsbruck, Kitzbühel, Villach, and Schwaz, with the interviews going on until 7pm.
The hearing also has room for 200 people in two public viewing sections, where the hearing is being transmitted live onto screens.
The Freedom Party filed the election challenge after their presidential candidate Norbert Hofer lost out by 0.6% of the vote to the independent Green-backed candidate Alexander Van der Bellen on the May 22nd run-off election.
The party claims the law was broken in 94 of Austria's 117 constituencies, including 82 where postal votes were counted too early, representing over 570,000 votes.
"We are not sore losers,” FPÖ leader Heinz-Christian Strache said when announcing the challenge. “This is about protecting the very foundations of democracy... The extent of irregularities is more than terrifying."
"You don't have to be a conspiracy theorist to have a bad gut feeling about this whole election... Without these glitches and irregularities Hofer could have become president."
The government election authorities said late last week there was no reason for the election to be repeated as there is no evidence of manipulation.
Expert on the constitutional court Theo Öhlinger told Der Standard newspaper last week that two of the complaints were “very serious”, including votes being counted by the wrong personnel and interim results being published online before the polling stations had closed.
The constitutional court has the power to decide whether to rerun the election if it thinks the irregularities could have influenced the result of the vote.