If the National People's Congress Standing Committee gives a stamp of approval - and it is likely to do so - it will be the third interpretation since the handover, and critics warn it will erode the rule of law and the 'one country, two systems' policy.

It will come on the heels of a similar government request on the right-of-abode provisions in 1999, and one initiated by the Standing Committee on universal suffrage on April 26 last year. Former Basic Law drafter, Maria Tam Wai-chu, said more interpretations could not be ruled out.

A prominent lawyer and veteran political figure, Ms Tam was among 23 Hong Kong elites who, together with their mainland counterparts, helped turn the concept of 'one country, two systems' into a legal document. Drawing an analogy on different electricity systems, Ms Tam described the Basic Law Committee as an adaptor that could help absorb differences and diffuse conflicts that may arise when the two legal systems interact.

The committee - comprising 12 members with six each from Hong Kong (including Ms Tam) and the mainland - advises on the interpretation and amendment of the Basic Law as required under the post-handover constitution.

With a third Basic Law interpretation in the offing, there have been grave concerns about its profound and far-reaching implications on the constitutional and political order.

The issue is no longer merely about whether the next chief executive should serve two years - the remaining term of the predecessor - or a full five-year term. It boils down to the inherent conflicts between the mainland's legal system and the common law, and, more importantly, the interface of the two systems under one country.

In a column of the Law Society's publication The Lawyer, society president Michael Lintern-Smith wrote: 'If it really means that five years can effectively become two years, then what effect could the application of such rules of interpretation have upon the other guarantees contained in the Basic Law which are so highly cherished by the Hong Kong population?'

He referred to remarks by Secretary for Justice Elsie Leung Oi-sie, which he said effectively meant the Basic Law should be interpreted not according to common law principles but according to Chinese law principles of interpretation. 'That assertion is disturbing and has far-reaching consequences. If correct, it would mean that no provision of the Basic Law can be read with any certainty by a common law trained lawyer,' said Mr Lintern-Smith.

At a Basic Law anniversary forum this month, Ms Tam said the issue of conflict in law interpretation was not new, adding it had been discussed in detail in the drafting process. 'Why are we still arguing about it now? One of the reasons is some people do not understand the other [mainland] legal system. They insist the NPC interpretation is not part of the legal system here and will damage the rule of law.

'The implementation of the Basic Law will be further improved through practice. Interaction between the two systems requires communication and candid discussion,' she said.

Reflecting on the twists and turns since the handover, another former Basic Law drafter, Raymond Wu Wai-yung, said Hong Kong people had only themselves to blame for their failure to win the trust of Beijing.

He recalled the dominant mindset among drafters was that Hong Kong should be given the maximum room for autonomous administration, while the central government kept its ultimate powers as a contingency.

'Beijing's optimism that Hong Kong people would behave well has proved to be wishful thinking. What it has done is adopt contingency measures and tighten its grip on Hong Kong affairs. After the July rally in 2003, Beijing had two options on Hong Kong affairs. First, they could take a hands-off approach and let Hong Kong people run the show. The second option was to intervene. As mainland legal experts have said, they would intervene from beginning to end,' Dr Wu said.

Relations between Hong Kong and the central authorities grew tense after half a million people joined a rally in protest against government blunders and unpopular policies on July 1, 2003. In a swift move to suppress the rising momentum of a democratic movement, the Standing Committee interpreted the constitutional development provisions in the Basic Law and ruled dual universal suffrage would not be introduced in 2007-08.

Dr Wu, who stood firm on his position that the next chief executive should serve five years, lamented the argument had become highly politicised. 'When you say it should be two years, Beijing says five. You say it should be five, Beijing says two,' he said. 'The Basic Law provisions will not be enough ... in safeguarding the well-being of people. It's vitally important to strive for the spirit [of the 'one country, two systems' policy to be adhered to] in the process of implementation.

'The first and foremost task after the handover is to establish a good relationship and win trust from Beijing. Like marriage, it won't last long if you always engage in a wrangle.'

Benny Tai Yiu-ting, associate dean of the University of Hong Kong's law faculty, said the conflicts in the implementation of 'one country, two systems' had become worse much faster than he had foreseen after the mid-2003 rally.

'As early as the 1990s, I felt increasingly that the conflicts in 'one country, two systems' would be irreconcilable. This [system] would only be possible if Hong Kong people gave up their important constitutional values, or if the Communist Party abandoned its one-party dictatorship,' he said.

'After 1997, we've seen constant tussles ... The people of Hong Kong have demonstrated their strong aspirations for democracy and change. It resulted in full-scale control by Beijing.

'It's fair to say Beijing has also changed. They know well they have power. At the same time, they understand the importance of them acting in a more civilised and open manner. They are more willing to engage with the community through dialogue. There's still a degree of self-restraint.'

Communication and seeking consensus are the buzzwords in the Standing Committee's damage-control drive before its meeting in Beijing next week, when it is expected to rule on the length of term for the next chief executive.

Speaking at a meeting with legal professionals including the Article 45 Concern Group in Shenzhen last Tuesday, senior NPC official Qiao Xiaoyang said the policy of 'one country, two systems' was an entirely new system and the Basic Law a brand new law.

'We will not be able to view and handle some conflicts in law if we do not have a new concept of rule of law and a new way of thinking ... The legal sector on each side should learn to think from the position of the other side. By doing so, it will help narrow the gap of differences and build consensus.

'The gap will grow if everyone only stands firm on the legal perspective and way of thinking they are familiar with and refuses to adjust their views in light of the new circumstances in the implementation of the Basic Law.'

Professor Tai, who sat on the then Basic Law Consultative Committee as a university representative in the 1980s, said differences between the two legal systems had been well understood.

'On the surface, it is a case of differences over the mechanism of interpretation of law. On a deeper level, it hinges on the fundamental contradictions under 'one country, two systems'.

'Under the common law, law is a tool to put limits on the powers of the government. Under the mainland system, the law is a weapon of power for the authorities to rule.'

He said the central authorities had considered the importance of self- restraint in exercising its powers over Hong Kong in drafting the Basic Law.

Under the mainland system, there are no mechanisms that could constrain the NPC's powers.

'The crux of the problem now is that the NPC Standing Committee has time and again asserted its authority and no longer restrains its power.

'Without any power to check the exercise of power by the Standing Committee, Hong Kong people can only influence the process through public opinion and mass movement. It results in a vicious cycle.'

Although grass-roots people seem to accept the interpretation decision, Professor Tai has warned of growing feelings of alienation and mistrust among the intellectuals and middle class towards the central and Hong Kong governments.

'Many of them feel politics is above the law on issues Beijing deems important ... It will create more difficulties in governance,' he said.

Dr Wu said a war over the two legal systems was the evolution of a new constitutional order. 'The tussle will go on for a long period of time ... Hong Kong people must wake up to the reality and find a new approach to deal with the mainland.'