After his press conference on Wednesday, Gary Cheng Kai-nam, vice-chairman of the Democratic Alliance for the Betterment of Hong Kong, might have convinced a few waverers that his worst offence was negligence. This morning, the picture looks far more serious. Following official confirmation that he passed on a confidential government paper given to him in his capacity as a legislator, Mr Cheng's reputation has suffered a body blow. Not only was the paper clearly stamped 'Confidential', but the official who passed it on sent an accompanying letter asking him to keep it that way. He chose to ignore both warnings. To add to that breach of faith, Mr Cheng has apparently betrayed his own party by passing on to one of his major clients an internal DAB paper on the Building Management Ordinance. Thirdly, he is reported to have alerted the same company, Li Ka-shing's Cheung Kong (Holdings), he was planning to raise a 'neutral' question in Legco on material transfer work in Ap Lei Chau in connection with the construction of the Cyber-Port. Much to the tycoon's annoyance, he too has become peripherally embroiled in the affair because, among Mr Cheng's other indiscretions, he proposed a scheme arranging to have people make calls to phone-in programmes praising the company. Mr Li was asked about the Cheng affair by reporters at a press conference announcing Cheung Kong's profit figures yesterday afternoon. Understandably rattled at questions unrelated to the matter in hand, Mr Li's reaction was perhaps made in the heat of the moment, and he repeated a previously made threat to stop investing in Hong Kong. After calmer reflection, Mr Li will no doubt recognise the injustice of making seven million people pay for the faults of one legislator, but his response is a reflection of how issues of this nature can spread to other areas like ripples in a pool. So much damning information, if confirmed, must cast doubts on the former legislator's political career. It is hard to see that he can have a future in the Legislative Council after this. His integrity has been deeply compromised. And the DAB is left to grapple with the thorny problem of how to respond to the crisis. Perhaps the best way for Mr Cheng to limit the fallout is by pledging to resign if elected in September. Under the electoral system, victory is still possible, though it could hardly be the convincing win he might have expected before this week's revelations. But all major parties have stalwarts who would vote for almost any candidate the party might put forward. Mr Cheng is a politician of acknowledged ability. He has always been held in high personal esteem, and many voters will quite correctly overlook his fall from grace in favour of supporting the DAB. But Mr Cheng's own political reputation is almost certainly beyond saving. He has failed to declare an interest when voting in a number of issues affecting his clients, including one involving mobile phone connections inside Kowloon-Canton Railway's tunnels. Voting along party lines is no excuse for breaching the rules of procedure. One oversight may be carelessness; a sequence of oversights is quite unforgivable. The episode has also thrown into sharp focus the unsatisfactory nature of the electoral process. Under the law, Mr Cheng cannot stand down at this stage. The running order cannot be changed. That is unfortunate for Choy So-yuk, who is running on the same ticket; she will most likely have to bear the brunt of another person's sins. So, to a lesser extent, will the DAB. Chairman Tsang Yok-sing will have to work hard to distance the party from his deputy's indiscretions before next month's poll. Because Mr Cheng must continue to run, that will be difficult to do. Mr Cheng's downfall is the more unfortunate because of his previous high profile as a conscientious legislator who looked as if he might well have gone on to higher things. But he has been guilty of more than mere foolishness. The matter is serious and the Government will have to look closely into the circumstances to see if any legal problems are involved. The mutual understanding between officials and legislators to pass on information given in confidence has been betrayed. Rules clearly state that a public servant must not use an official position to gain advantage. But there seems little doubt that Mr Cheng violated the trust placed in him as a legislator to further his role as a public relations consultant. The two jobs simply are incompatible. The Government, as well as Legco, should look again at the regulations to see whether lawmakers should be prohibited from work of that nature. More seriously, voters will want to know whether any offence has been committed under the Prevention of Bribery Ordinance.