The resignation of Tung Chee-hwa has widely been seen as an opportunity for Hong Kong to move on from the troubles of recent years and make a fresh start. The outgoing chief executive, announcing the decision last week, stressed it had been taken in the city's best interests. But Mr Tung's departure has had unexpected consequences. It has plunged Hong Kong into a new constitutional crisis which could have serious implications for the future of the 'one country, two systems' concept. The government has suddenly changed its view of a crucial part of the Basic Law. It concerns the length of the new chief executive's term. Previously, the government had stated that this could only be five years. But it changed its mind after consulting with mainland experts. Now, the government contends that the new leader should only serve out the remainder of Mr Tung's term. Five years, it seems, has been turned into two. Critics of the move say it has betrayed Hong Kong's legal system, undermined the rule of law and damaged the city's autonomy. This, they argue, is a political decision made by the central government in flagrant breach of the law. 'They did not do it according to the proper legal procedures. Someone shouts his mouth off in Beijing and the Hong Kong government scrambles to turn its own opinions around. It is ridiculous,' said Ronny Tong Ka-wah, SC, a legislator with the Article 45 Concern Group. There has been strong support for a five-year term within Hong Kong's legal community. But different opinions have also been expressed. Some lawyers have, like the government, changed their minds on what they see as the interpretation of the Basic Law, after hearing what mainland experts had to say. Others say that the meaning of the law is unclear and that the National People's Congress Standing Committee is best placed to say what was really intended. 'The interpretative power of the NPCSC has been unfairly demonised. We should not live in fear of it,' said Alan Hoo, SC, a Hong Kong member of the Chinese People's Political Consultative Conference. The controversy highlights the problems which arise when Hong Kong's common law legal system comes into conflict with the very different principles which apply on the mainland. It has sparked renewed calls for steps to be taken which will promote understanding on both sides and avoid further constitutional crises. But a solution is not easy to find. At the heart of the battle over two years or five years lies the text of the Basic Law. This had, until a few weeks ago, appeared to provide an answer which was crystal clear. There is only one article in the constitution which refers directly to the length of a chief executive's term. This is Article 46. It says: 'The term of office of the chief executive shall be five years.' Until very recently, the government took the view that this means only a five-year term is possible. The Chief Executive Election Ordinance, under which Mr Tung was elected in 2002, was based on this view of the law. If there was any doubt, Secretary for Constitutional Affairs Stephen Lam Sui-lung appeared to have dispelled it last May. He told lawmakers: 'The term of office of the chief executive, as prescribed in the Basic Law, is five years. This provision applies to any chief executive. There is no exception.' But last weekend, Secretary for Justice Elsie Leung Oi-sie announced that the government had altered its thinking after consulting mainland experts. She admitted the 'five year' verdict had been based on the common law approach that 'clear and unambiguous' legal provisions should be interpreted according to their ordinary meaning. Ms Leung added: 'After thorough study and deliberation, the government has adjusted its understanding.' The secretary for justice seemed to suggest that the views of mainland experts can override the Basic Law. This has prompted a strong reaction from lawyers in Hong Kong. Senior Counsel Gladys Li said: 'What is dangerous about this is that we are getting more and more knocks to the common law approach.' Ms Leung said she had put the common law position to the mainland experts. But Ms Li said: 'It was really a case of roll over and die.' Bar Association chairman Philip Dykes said: 'I found the Secretary for Justice's reasoning alarming.' In almost every legal system, he added, the law is supposed to mean what it says. 'The legislative intent is expressed through words, not thoughts,' he said. 'You don't start with an intention and then say: If the words don't fit, never mind. This is totally alien to our system.' Mr Dykes said the Basic Law provided for a five-year term. 'There appears to be no ambiguity.' So what were the opinions which caused the government to change its mind? The case for two years rests on a combination of the political structure provided for by the Basic Law, last year's interpretation on political reform by the NPCSC, the practice on the mainland and records of the drafting process. Solicitor-General Robert Allcock said there was a 'respectable case' to be made for two years, even if common law principles were used. The starting point, he said, was that the wording of the Basic Law was not as clear as it first appeared. He argued that while the constitution provided for a five-year term in normal circumstances, it did not spell out what was to happen when a chief executive stepped down mid-term. 'I don't think we are turning black into white,' he said. Mr Allcock said a five-year term starting now would not make much sense in the light of other provisions of the Basic Law. For example, the Election Committee, which chose the chief executive, was given a five-year term which would end in July. If it chose a new leader who could serve until 2010, it would be going beyond the mandate provided in the Basic Law, he added. Then there is the question of constitutional reform. Mr Allcock argued that a two-year term would be more in keeping with international human rights safeguards because it would allow a more representative electoral system to be put in place for an election in 2007. 'The possibility of democratic reform in 2007, which is clearly contemplated in the Basic Law, would be frustrated if the next chief executive had a five-year term,' he added. Mr Tong, however, dismissed any notion that the imposition of a two-year term could be seen as advancing human rights. 'This is very admirable. But it does not accord with reality. Nothing very much is going to happen in 2007 anyway,' he said. Ms Li said the arguments about the mandate of the Election Committee were merely 'political considerations'. She added: 'It has absolutely nothing to do with what the law means. This is really scraping the bottom of the barrel.' The solicitor-general put his arguments in favour of two years mainly on the basis of common law principles. Other advocates of the shorter term place greater emphasis on the role of the NPCSC and the use of mainland principles. A paper released by the Basic Law Institute yesterday argued that the appointment of the chief executive was a matter which fell outside Hong Kong's autonomy. Therefore, it said, the relevant parts of the Basic Law were 'a matter for interpretation by the NPCSC'. The institute added that if a formal interpretation was made by Beijing, 'the principles of construction adopted by the NPCSC may well be different from those applied by our common law courts in Hong Kong'. When considering an interpretation, the NPCSC might take into account various matters, it added. These could include the mainland practice of allowing vacancies in high office to be filled only for the remainder of the term, the mandate of the election committee, and last year's decision by the NPCSC on political reform - which stated that the third term for the chief executive would be in 2007. The battle over two years or five years seems set to continue. There is also the possibility of a legal challenge in the courts, which could potentially derail this year's election plans or prompt an interpretation from Beijing. This is the third constitutional crisis since the handover, after the controversies over the right of abode in 1999 and political reform last year. Once again, people are wondering how this situation could have arisen and whether future clashes can be avoided. 'I think all concerned should share a measure of responsibility,' said Mr Hoo, referring to the current controversy. 'Legal opinions on both sides took entrenched positions too early. No opportunity was afforded for their to be a mutual exchange of opinions and for their to be a constructive and meaningful dialogue. 'The Hong Kong government certainly did not look at this matter thoroughly enough in the past. This is a matter of constitutional importance. It should have consulted the mainland experts before the election ordinance was tabled.' He added that the central government should also recognise that the legislative intent of the relevant provisions was not apparent. 'They should perhaps be more accommodating and sympathetic to the common law perspective in Hong Kong. The mainland legal experts opinion only reflects the mainland approach.' Mr Hoo said much more should be done to research the drafting history of the Basic Law and to gain a better understanding of its meaning. Lawyers on each side of the border should get together more to discuss these matters in order to avoid future wrangles. 'Those in the common law camp tend to take one position and the mainland experts take another. That is precisely what should not happen under 'one country, two systems'. There should be an interface to make it work. Who suffers when there is confrontation? The answer is Hong Kong society.' The solicitor-general said: 'We all saw the embarrassment of doing a U-turn, as the media likes to call it.' But he said the government should be cautious about frequently seeking the advice of mainland legal experts. 'This is highly sensitive. People would be concerned if we were doing this too frequently because they want to preserve Hong Kong's autonomy.' Beijing's right to interpret the Basic Law is a 'legal reality' which cannot be ignored, said Mr Allcock. The Court of Final Appeal is obliged to refer articles which fall outside Hong Kong's autonomy to the NPCSC when it needs to interpret them to decide a case. The solicitor-general said the government might seek mainland advice when considering these articles. But he added that it was 'crucial' to point out that human rights provisions would not fall into this category. 'As far as the courts are concerned they will apply common law principles unless there is an NPCSC interpretation,' said Mr Allcock. He added: 'As far as we are concerned we will also apply common law principles unless there is either an interpretation or - in the case of an article outside our autonomy - there is the clearest indication of the way the NPCSC would rule.' But this is unlikely to reassure the doubters. Mr Tong said: 'You are talking about the appointment of the chief executive, the most crucial appointment in Hong Kong. And they mess it up like this. I am very pessimistic. But we will keep on fighting.'