The SAR's highest court yesterday freed a convicted Ecstasy dealer to undo a 'substantial and grave injustice' by those who jailed him. Mark Seabrook, 39, vowed he would never again get involved in illicit activities after the Court of Final Appeal ruled in his favour. 'I just feel finally justice has been served,' he said. 'But if I didn't push it, I think I would still be languishing in jail.' Mr Seabrook was jailed for four years and four months in May 1997 for selling an undercover police officer 352 Ecstasy pills. He has been on $100,000 bail since he was granted the right to appeal to the highest court in November. Mr Seabrook initially was refused an appeal to cut his sentence based on new evidence that Ecstasy was neither addictive nor particularly toxic. The expert evidence - which came to light in an appeal by another dealer - led to new sentencing guidelines for the rave drug, which was previously treated as seriously as heroin and cocaine. Chief Justice Andrew Li Kwok-nang, Mr Justice Henry Litton, Mr Justice Charles Ching, Mr Justice Kemal Bokhary and visiting judge Lord Nicholls ruled that the Court of Appeal erred when it applied the guidelines to two other dealers but not Mr Seabrook. Mr Justice Bokhary said an extreme case of this kind had to be heard by the court 'in order to undo a substantial and grave injustice'. 'Even if some increase were to be made on the footing that [Mr Seabrook] imported the drugs into Hong Kong, his total sentence could not properly be left at anything more than two years' imprisonment,' the judges said. 'Society has no interest in imprisoning people unnecessarily or keeping them in prison longer than necessary.' The lower court said cutting Mr Seabrook's sentence to bring it in line with the guidelines would open the gate for a flood of appeals. 'Should we be afraid of undoing an injustice just because there might be another 99 injustices to be undone afterward?' Mr Justice Bokhary said in the latest hearing. Mr Seabrook said yesterday: '[Jail] has taught me to be more careful who I trust. It taught me also to never get involved in any kind of illicit business.'