Close results in constituencies at the election could be challenged in the high court because of delayed postal votes, experts have said.
Caroline Morris, a barrister and reader in public law at Queen Mary University of London, said people could get a hearing if four constituents petition the high court arguing their vote could have had a material impact on the result.
The prospect of legal challenges comes as thousands of voters have complained of not receiving their postal votes on time. In Scotland several councils have opened special units to provide duplicate ballot papers.
Jane Golding, co-chair of the campaign group British in Europe, said members had complained about delays in proxy votes arriving.
Pete Jones, a British citizen who lives in Switzerland with his partner and daughter, condemned the “utter incompetence from those involved in the organisation of postal votes”.
Two of his family received their ballot pack on different days but he has yet to receive his, leaving him with no possibility of voting unless he flies back to the UK on Thursday.
Morris said the system appeared to be under “a great deal of strain”, partly because of the compressed timetable for the election.
A judge could open a fact-finding inquiry to assess whether a re-run of a vote should be called. In an egregious case a judge has powers under the Representation of the People Act 1983, part III to call for a new ballot straight away.
While the bar is high and courts will not order re-runs in general, it is not without precedent, said Morris.
In 1997, there was a re-run in Winchester when the Liberal Democrat Mark Oaten won with a majority of just two votes. After a legal challenge over an administrative bungle that left 54 ballot papers not stamped correctly, the high court ordered a fresh ballot and Oaten was elected with a majority of more than 21,000 seats.
In 2015 Diane Abbott also faced a legal challenge after registration papers did not show up at polling booths, meaning some voters were denied their chance to participate in the election.
However, Morris said the challenge was unsuccessful as it was deemed that a re-run would not have changed the result because she had a commanding majority.
She said: “It’s very hard [to get a re-run] but not impossible. The court has to answer two questions. First of all, has there been a breach of electoral law? Then there are administrative irregularities and the court would have to establish what went wrong.
“But the main question is whether the error made a material difference to the outcome of the election? If the loss of postal votes [is] in a particular constituency where the contest is very narrow, then it could make a difference.”
She also said the “compressed timetable” for this election puts “pressure on people to get things done quickly and when people do things quickly mistakes can be made”.
“Even if everything is done correctly, and you are relying on a third party such as the Royal Mail and they make a mistake, the impact of that is compounded because of the lack of time,” she said.
Councils could not legally do anything before the deadline for candidates to register closed on 7 June, or complete list of ballot packs for postal voting until the deadline for applications closed on 18 June.
They were able, however, to send out postal packs earlier to those who had registered for votes earlier or had long-term postal option in place, the Electoral Commission said.
A South Ayrshire council spokesperson said: “We are aware of delays nationally with postal votes.
“The delays have not been a result of local processes, and South Ayrshire council have taken urgent steps to ensure that, where possible, all residents can cast their vote on Thursday.”
