Lippo Group deputy chairman Stephen Riady is planning a legal challenge to the insider dealing tribunal's powers after being drawn into one of its inquiries. Last July, an inquiry was set up to determine whether Worldsec International director Carlton Poon and two others profited from inside information. The inquiry then turned its attention to Mr Riady's alleged role in trades of HKCB Bank Holding and Lippo China Resources shares. Mr Riady - also chairman of Hong Kong-listed Lippo and deputy chairman of Lippo China Resources - was not named in the original inquiry. Tribunal chairman Mr Justice Gareth Lugar-Mawson held there was material 'which suggests Mr Riady is a potential insider dealer in that he counselled or procured Mr Poon to engage in insider dealing in the listed securities of the two companies'. The material is in the form of a provisional expert witness' report prepared on behalf of Mr Poon. A letter was sent by the tribunal to Mr Riady asking him to appear before the tribunal. This sparked a challenge to the ambit of the inquiry. Mr Justice Lugar-Mawson has upheld the tribunal's jurisdiction, saying 'the terms of reference are sufficiently wide' to include Mr Riady. He gave his decision on the question of law last month. A lawsuit will, however, be lodged in the High Court to challenge the judge's ruling on the tribunal's power to draw people into an inquiry and make a finding of insider dealing. 'There's going to be a judicial review - we have told the tribunal that,' said barrister Gerard McCoy, counsel to Mr Riady. 'If the financial secretary wants to name you [in an inquiry], he puts your name down,' he said. 'We say it's wrong in jurisdiction.' Mr Riady could not be reached for comment. The challenge could spark a rash of similar lawsuits if successful, taking the tribunal to task over previous decisions to spread its inquiries. The issue goes to the core of the tribunal's powers. Its jurisdiction has always been assumed to be wide, with laws stating the tribunal can simply 'determine the identity of every insider dealer' and punish them accordingly. The tribunal is no stranger to controversial legal challenges. These have ranged from the level of penalties imposed - the highest to date has been HK$47.4 million - to the conduct of the hearings. The most high profile was the Paragon Holdings case in 1998 where the findings were thrown out after it emerged the bulk of the hearings had been held in secret. It was estimated to have cost taxpayers HK$40 million.