Lawyers are trying to recoup hundreds of millions of pounds for energy customers who lost out because of the dealings of several cable sellers.
They have filed a class action lawsuit hoping to prove that households overpaid for their energy.
In 2014, the European Commission found that several companies which sold high voltage and underwater electricity cables between 1999 and 2009 had been running a nearly worldwide cartel.
It meant that energy companies in Britain overpaid for their cables, costs that were ultimately passed on to customers.
The suit is being run by lawyers from Scott + Scott, who were instructed by Clare Spottiswoode, who was head of regulator Ofgas in the 1990s.
Without collective proceedings like this, UK consumers would have no reasonable way of recovering damages for the harm suffered by serious anti-competitive practice further up the supply chain
“Domestic electricity customers in Great Britain paid inflated energy bills for many years through no fault of their own,” Ms Spottiswoode said.
“This is manifestly unfair. Without collective proceedings like this, UK consumers would have no reasonable way of recovering damages for the harm suffered by serious anti-competitive practice further up the supply chain.”
James Hain-Cole, from Scott + Scott, said: “This is a complex and meticulous claim, bringing together some of the foremost lawyers, economists and industry experts in the field. We are highly confident in the strength of our case.”
The case will be taken to the Competition Appeal Tribunal, and anyone who has been a bill-payer in Britain since 2001 is eligible to be included in the suit.
Lawyers hope they can recoup hundreds of millions of pounds, but did not give a precise figure.
Ms Spottiswoode said: “I hope this will send a warning sign to any corporates who might contemplate anti-competitive behaviour in future and will recover appropriate redress for consumers who lost money as a result. I am fully confident in the importance and strength of this claim.”
