BY any civilised standards China's decision to jail journalist Wu Shishen for life for selling, to a Hong Kong colleague, an advance copy of a speech by the Communist Party leader is a punishment out of all proportion with the gravity of the crime. Italso renews long-standing fears over the independence of the mainland judiciary, which has handed down a particularly harsh sentence because of the intervention of Jiang Zemin. Although judicial authorities had wanted to jail Wu for 10 years, Mr Jiang insisted on a heavier sentence. It also adds another human rights blot to Beijing's already badly spotted copy-book with less than a month to go before the decision on whether China should be allowed to host the 2000 Summer Olympics. Moreover, at a time when the Han Dongfang case is causing ripples in Washington, it is yet another testimony to China's inability - or unwillingness - to understand the damage such displays of intemperance inflict on its own international image. However, some caution is required in condemning China outright. While Beijing's reaction is undoubtedly excessive to a cruel and unusual degree, this is no simple case of a totalitarian and oppressive state cracking down on press freedom. If it is true that the document was sold to a Hong Kong reporter for 5,000 yuan - a charge her newspaper, Express Daily, has denied - the crime is more than mere journalistic over-enthusiasm. To put it at its most charitable, it is a sign of China's growing corruption. To the secretive and over-sensitive Beijing leadership, it must appear close to espionage. As a sub-editor at Xinhua (the New China News Agency) Wu was, above all, a government employee. But, again, even if the accusation is true - and the secrecy of the trial means no evidence of a ''sale'' has emerged in open court - the leak hardly justifies life imprisonment. As Hong Kong Journalists' Association chairman Daisy Li Yuet-wah has pointed out it caused no serious damage to China's national interests nor did it undermine national security. If this speech - even by the General Secretary of the Party - is to be considered a state secret of such importance, then the secrecy itself is oppressive and excessive.