Jailed socialite Mo Yuk-ping has won the right to challenge the validity of one of her convictions in the city's highest court. The Court of Appeal yesterday granted Mo, who was jailed for 31/2 years last January, a certificate to argue in the Court of Final Appeal that one of the charges she was convicted for was unconstitutional. Mo, the wife of disgraced Shanghai Land chief Chau Ching-ngai, was found guilty on two counts of conspiracy to defraud possible investors, earning her concurrent two-year sentences, and one of perverting the course of justice, which earned her another 11/2 years. The Court of Appeal overturned one of the conspiracy charges last November on the grounds that the trial judge had failed to make the necessary findings for a conviction based on the prosecution's case. It earlier rejected an argument from Mo's counsel, London QC Clare Montgomery, that the charge of conspiracy to defraud was unconstitutional because its definition was so broad it rendered it nearly impossible to draw a line between criminality and legitimate business activity. The certificate granted yesterday - on the grounds that it was a point of great and general public importance - will allow that argument to be fully thrashed out in the Court of Final Appeal. The judges - Court of Appeal justices Frank Stock and Wally Yeung Chun-kuen, with Mr Justice Aarif Barma of the Court of First Instance - rejected four other grounds of appeal in reaching their decision.