Nigel Farage’s Brexit Party is going to court to challenge the result of the by-election in Peterborough earlier this month. Such a move is high profile, but very difficult to prove and can be risky even if successful.

At the time of the election, the Brexit Party, which lost by 683 votes, claimed that there had been fraud connected with postal votes. Five complaints have been made to police – although it is not clear whether any or all of these have been made by the Brexit Party – and so far three of these complaints have been dismissed.

Both Nigel Farage and Brexit Party chair Richard Tice have spoken in broad terms about corruption linked to the by-election, but have not given any specific details of what they allege took place. Mr Tice is quoted in the Guardian as saying:

“There are a lot of rumours, a lot of hearsay, some of which is just that. There is evidence emerging. That will be presented to the electoral court. It’s wrong to prejudge that, or announce that now. It’s only by having a full petition that we can truly get to the bottom of what may or may not have happened here, but also the lessons for the broader system.”

Election watchers in the UK will be looking closely to see what details emerge if the election petition is lodged as the Brexit Party have said it will be. In order to make any progress, the party will need to be able to make and prove detailed and specific allegations. Even then, the result will only be overturned and a fresh election ordered if the judge is convinced that the outcome has been affected by illegal activities. Even if the Brexit Party were able to prove that some fraudulent votes were cast (itself a high burden), it does not mean that a re-run would happen.

When new elections do happen, it does not always go to plan for the party which has brought and won the court case. The most recent case concerning a Parliamentary election was in Oldham East and Saddleworth in 2010 when former minister Phil Woolas was found to have made untrue statements about an opponent. Voters backed Labour in the re-run. And in 1997, after the Conservatives brought a court case over the result in Winchester where they were declared to have lost by 2 votes, the re-election produced a much more emphatic result – the small matter of a 21,556 majority for the Liberal Democrats.