Prime Minister Shinzo Abe is rushing to keep his promise, made in the United States Congress, to enact new security laws by the end of September to enable Japan's Self Defence Force (SDF) to go to the aid of friendly nations under attack.
But constitutional scholars maintain that Mr Abe's draft security legislation is unconstitutional since it is based on a re-interpretation, and not a revision, of Japan's war-renouncing Article 9 to give the SDF the right to exercise collective self- defence. They say Mr Abe must not take the easy way out with a mere change in the government's longstanding interpretation of Article 9, backing that up with a Cabinet decision.
Revising the Constitution requires the two-thirds approval of the Lower and Upper Houses of Parliament and a majority in a national referendum, conditions that have not been met in Japan so far. The Bills cleared the first hurdle - the Lower House - yesterday.
Until Mr Abe came along, Article 9 was interpreted as limiting Japan's military capability to the minimum needed for its defence. But he claims the increasingly severe global security environment justifies a re-interpretation.
Mr Abe, who leads a two-party coalition that controls two-thirds of the Lower House, had thought his attempt to give Japan a new security framework and allow the SDF to engage in joint military operations with the US and other countries would be plain sailing.
Following standard practice, three scholars were last month asked to give their opinions in Parliament on the security Bills.
The two scholars fielded by the opposition camp were known opponents of the Bills. But Mr Abe and his Liberal Democratic Party (LDP) were stunned when Professor Yasuo Hasebe of Waseda University, whom they had handpicked and expected to uphold the Bills, also branded them unconstitutional. The Bills would "considerably damage the legal stability" of Japan and violate its post-war pacifist Constitution, Prof Hasebe said, adding that more than 95 per cent of constitutional scholars in Japan share his view.
NO IGNORING THE CONSTITUTION
We must realise any policy discussion that ignores the Constitution is tantamount to ignoring the people.
PROFESSOR SOUTA KIMURA, Tokyo Metropolitan University
Observers suggest Prof Hasebe was trying to distance himself from the Abe administration, after having been labelled pro-Abe when he spoke in support of the Prime Minister's controversial Official Secrets Act passed in December 2013. Critics say the law allows the government to hide embarrassing information from the public.
HIGH STAKES FOR ABE
The stakes are very high for Mr Shinzo Abe. If he fails to deliver on the Bills, he may lose US President Barack Obama's support, which would be a huge blow to the Abe government.
If he rams the Bills through Parliament as expected, his public support is likely to fall even further.
Polls show only a handful of constitutional experts support Mr Abe. Professor Souta Kimura of Tokyo Metropolitan University has said: "We must realise any policy discussion that ignores the Constitution is tantamount to ignoring the people."
More than 9,000 academics, in addition to thousands of citizens, have signed an appeal opposing the security Bills, which they see as not just unconstitutional, but also an attack on the key principles of constitutionalism and the rule of law in Japan. There have been huge rallies in Tokyo and other cities against the draft legislation, which critics have dubbed "war Bills".
But Mr Abe is unfazed and has enlisted the help of international law experts to speak up for his Bills.
He said on an LDP Internet broadcast on Monday: "It is not legislation for going to war but the complete opposite."
A Mainichi Shimbun poll has found 81 per cent of the people thought the government had more explaining to do over the Bills.
Local Revitalisation Minister Shigeru Ishiba, who is also Mr Abe's political rival in the LDP and an expert on security issues, has said that, given the poll figures, it is difficult to claim the public is convinced the Bills are necessary.
This week, Mr Abe reluctantly admitted in the special Lower House committee deliberating the Bills that public understanding of the issue was still insufficient.
But there is no stopping Mr Abe.
He has extended the parliamentary session to Sept 27 - the longest extension in Japan's post-war history - to allow sufficient time to get the Bills through both Houses. After clearing the Lower House, the Bills will be sent to the Upper House. If they are then rejected , they will be sent back to the Lower House, where Mr Abe's ruling coalition has the requisite two-thirds majority to override the Upper House decision.
But Mr Abe has not heard the last from constitutional scholars.
Keio University's Professor Emeritus Setsu Kobayashi is working with a group of lawyers to bring a suit of unconstitutionality against the Abe administration.
The stakes are very high for Mr Abe. If he fails to deliver on the Bills, he may lose US President Barack Obama's support, which would be a huge blow to the Abe government. If he rams the Bills through Parliament as expected, his public support is likely to fall even further.
The NHK network's latest poll found only 18 per cent of support for Mr Abe's move to enact the security laws. The same poll showed his approval rating has fallen to 41 per cent - the lowest since he took office in December 2012.
Former LDP stalwart Makoto Koga has said "Abe is increasingly like a dictator", and called the Abe regime "dark and creepy".
Prof Hasebe told Reuters: "I think Mr Abe hates the concept of modern constitutionalism, that the powers of the government should be restricted by the Constitution."
Mr Abe may well go the way of his maternal grandfather Nobusuke Kishi, who was obliged to quit as premier two months after he forced a new US-Japan security treaty through Parliament in May 1960, amid widespread street protests.