An unsuccessful Labour candidate is taking Croydon Council to court, calling for a new vote in the Waddon ward.
David Christison, who was granted legal aid for his case, issued the election petition to Jon Rouse the Chief Returning Officer after residents missed out on their right to vote because of long queues in the ward.
He was one of the three Labour council hopefuls who stood for election in Waddon, historically one of the most marginal wards in the borough.
In the May 6 election, the incumbent Conservative candidates held onto their seats.
Mr Christison polled 500 fewer votes than his nearest Conservative rival.
An internal council inquiry estimated about 80 people were unable to vote because of the queues outside stations in Barrow Road, Waddon and Valley Park, Broad Green.
The chief returning officer, Jon Rouse is expected to appear before a High Court judge in July to answer the legal challenge in a preliminary hearing.
The judge will then decide whether to hold a full hearing into the matter which would occur in the autumn. If Mr Christison is successful, a by-election would be held in the ward.
Mr Christison, who polled 1,927 votes, said: “Being denied the right to vote, a right people have fought and died for, is a scandal. Whether it was 80 people as the Council claim their ‘initial’ investigation has found, or 800, then it is an outrage.
“However, if, as I suspect, it is many more than the Council claim, then it is a challenge to democracy itself and is quite simply unacceptable.
"Being denied your right to vote is also a clear breach of human rights and it must be in the public interest that this injustice is challenged."
A council spokesman said: “We have received the election petition and respect the legal right of any candidate to challenge an election result.
"Through our insurance company we will be defending the case vigorously.
"We are concerned that some individuals' descriptions of events on May 6 are becoming increasingly exaggerated.
"Of course, we regret that a small number of people were unable to vote. It will be a matter for the court to decide whether that made a difference.”
Were you unable to vote? Contact the newsdesk on 0208 330 9559