The court's decision to repeat elections in the district of Leopoldstadt comes after Austria's Freedom Party challenged those elections in November 2015.
Just a few weeks ago, the party have also separately challenged the Austrian Presidential elections.
The re-election announced today, however, has no bearing on the result of the challenge against the Austrian Presidential elections.
The challenge regarding the local election in Vienna was related to a discrepancy between the amount of ballot papers and the amount of votes cast.
After the first count, the electoral authority counted 82 ballots less than the number of votes cast. A second count, however, showed 23 ballots more than votes casts.
It still remains unclear how these discrepancies came about. However, the court concluded there is no doubt that the observed discrepancies are a violation of the Vienna election regulations and thus there has been a breach of law.
The court can only uphold the challenge, if the breaches of law could have influenced the results of the election. In relation to this election, this is the case.
Although the Social Democrats were first in local elections, the Greens and the Freedom Party were neck to neck for second place with 10,031 and 10,010 votes respectively.
With a discrepancy of 23 votes, the outcome of second place - and therefore the role of District Deputy - could have been influenced by the mistakes made during the counting, according to the VfGH.
The re-election will take place in the whole of the 2nd district. A repeat of only postal votes is not an option. This is because it cannot be determined without a doubt which voters send their ballots by post, as one can apply for a postal ballot but then still vote in person.
The re-election will likely take place sometime in September as the summer holidays are coming up and time is needed to prepare for the election, the Head of Vienna's Electoral Authority Andreas Mailath-Pokorny told the ORF.
The Freedom Party filed a challenge against the Presidential elections, citing irregularities with the counting of postal votes. The proceedings for this case will take place in the upcoming week.
Written by: Helena Uhl