Brian Loveridge, 58, was banned from voting or standing as an election candidate for five years after being found guilty of an offence under the Representation of the People Act 1983, despite his protests he had no idea his actions were prohibited by the strict electoral laws.
Since the ruling, made in June 1996, he has persistently battled to overturn the election court's finding, taking his case to London's high court in January this year, and when that bid ended in defeat, to the court of appeal.
Stunned and outraged at yesterday's refusal by three appeal judges to interfere with the ruling, the former miner, is now vowing to take his campaign to Europe.
Mr Loveridge, who stood for the Aberamon South ward, was declared the winner, polling 687 votes against the rival Plaid Cymru candidate Howard Davies' 686 but after the election a complaint was made that he had given an interview to the BBC which had been broadcast on television and radio the day before the poll.
The interview concerned the Abercumboi waste tip site within the ward and had been given to the BBC on November 17, and it was argued Mr Loveridge's participation breached the election laws because permission had not been given by the rival candidate, although no reference had been made to the coming election.
At the election court hearing held to determine the validity of the bye-election Mr Loveridge insisted he had not taken part to 'promote or procure' his success in the poll.
He maintained he simply stepped into the breach at the last minute when a planned interview with Friends of the Earth over the tip fell through, and he had been selected because his mining experience gave him specialist knowledge of the site's geology, not because he was an election candidate.
And he maintained he had had no idea the interview could jeopardise his election or result in such harsh penalties.
But in a decision given on June 7, 1996, the court's commissioner Peter Brunner QC, found against him, resulting in the automatic five-year-ban on voting, standing as a parliamentary candidate or standing as a prospective councillor for an authority covering the Rhondda Cynon Taff area, as well as invalidating his election to the council.
Today, urging Lords Justices Stuart-Smith, Henry and Aldous, to grant leave to mount a judicial review challenge to the election court's finding, his counsel, David Bean QC, said his client still maintains he never intended to influence the voters by giving the interview.
He said: 'He rightly feels the finding is hard when it concerns an interview where his name wasn't heard or his party named.'
But, he added, Mr Loveridge reluctantly accepted he could not challenge commissioner Brunner's finding he had taken part 'to promote or procure' his success because parliament has provided no appeal on election courts' findings of fact.
Instead, said Mr Bean, he challenged the ruling on the ground the commissioner had erred in law by finding Mr Loveridge had consented to the broadcast being transmitted, because he had at no stage given an express consent to the transmission.
But all three judges dismissed the argument, ruling Mr Loveridge had consented to the transmission by taking part in the interview and making no attempt to stop it before it was broadcast.
Giving judgment, Lord Justice Henry said he appreciated Mr Loveridge's case 'is that he had no idea that what he was doing was unlawful at the time but he reluctantly accepts that would give him no defence.'
Outside court, in a prepared statement to the press, Mr Loveridge said: 'The offence I have been found guilty of has been committed many times by all parties, and by experienced and inexperienced councillors.
'I believe I have been severely reprimanded for representing the rights of local people and intend to take this matter to the European court.'