The 57-year-old knows well how Beijing thinks.

"Some pan-democrats may have a hope, or I'd call it a fantasy, that if they veto [the package] this time, they may, by 2022, get a better or more democratic framework than [last year's]."

With Xi Jinping almost certain to still be the country's president by then, Chen said there was little chance that Beijing would suddenly lower the threshold a few years later.

Plus, there is no guarantee that Beijing will allow another consultation if this one fails.

"Democracy has to have a start," Chen said. "The right to vote itself can play some role even though the nomination procedure is restricted. People's power and people's voices can be amplified on a larger scale."

That wouldn't be the view of the likes of US democracy expert Professor Larry Diamond of Stanford University's Hoover Institution, who likened Hong Kong's likely election system to Iran's, where the Guardian Council, a body appointed by the supreme leader, decides who can run for president.

"This is democracy," Chen said. "It is up to the voters to decide which of the three [or so candidates] would take the job. How would this not be democracy?"

Chen added: "Overseas scholars do agree this is democracy."

Hongkongers, he said, should wake up to the reality that the city is under Chinese sovereignty, so the master does have a final say over who gets the top job.

Chen pointed to two chances for Hongkongers to influence the election. The first is at the initial stage of the nomination process, when a maximum of eight candidates are generated for the nomination race - a stage when people can take part in public opinion polls to let the nominating committee see which two to three receive the greatest support.

The second is during the election itself. Under Chen's proposal, if voters are not satisfied with any of the candidates put forward by the nominating committee, they can cast a "none-of-the-above" vote, and if enough such votes are cast, the election can be declared void, putting the committee and Beijing in an embarrassing position.

Chen used to advocate more liberal reforms.

Two years ago, he suggested the abolition of corporate voting for choosing members of the nominating committee, and allowing as many as five candidates to appear on the ballot. Beijing has since decided that the number of candidates should be capped at three, and these need the support of at least half of all nominating committee members.

Chen said he believed the restrictive approach was the result of Occupy Central, and any mutual trust between Beijing and pan-democrats had dissipated since then.

Chen also noted that there had always been a conservative faction on the mainland which believed the city shouldn't be given greater democracy lest the mainland public demand it.

"I told [mainland officials] that Hong Kong people are rational and pragmatic, and they will not elect someone who confronts Beijing."

But there is a set of figures that worries the central government - pan-democrats have always won some 50 to 60 per cent of all votes in Legislative Council elections, causing the nervous master, in Chen's words, to "worry about a victory of a pan-democrat who does not love the country and love Hong Kong" in the chief executive election.

Since 1984, the year in which the Sino-British Joint Declaration on Hong Kong's future was signed, Chen has been a constitutional law scholar, an expertise that finally led to him becoming dean of the University of Hong Kong's law faculty, overseeing the 1997 handover for the school.

As an avid reader of history, Chen - who will retire in about two years - notes that no democracy has ever emerged without struggle. He points to Japan, South Korea and Indonesia.

"Today, I feel that the practice of 'one country, two systems' is facing an unprecedented crisis," Chen said in an October broadcast on RTHK. "The road ahead for 'one country, two systems' seems to become narrower and narrower, more and more difficult to walk."

Like all seasoned intellectuals, Chen declined to impose a label on himself, refusing to say if he's an optimist or a pessimist.

"What I've been doing is merely to devise something as democratic as possible within the legally acceptable boundary."

This sense of realism attracts different reactions. Civic Party lawmaker and former Bar Association chairman Alan Leong Kah-kit called Chen "a person who has long resigned himself to the fact that we are no match for the Communist Party in a David and Goliath situation".

Chen, he said, was "advising us to kneel down".

But Professor Michael Hor, the current University of Hong Kong law dean, praised him as a man of wisdom.

"Although he is quite capable of being intensely cerebral, I have come to be even more impressed by his overarching sense of humanity and compassion - the person always comes before the idea," said Hor, who first met Chen at Kyushu University in Japan some 15 years ago.

Back then, Hong Kong's legal system was rocked by a National People's Congress Standing Committee interpretation of the Basic Law which effectively overturned a Court of Final Appeal decision on right of abode for mainlanders.

As a member of the Basic Law Committee, Chen has been involved in deliberations on all four interpretations of the Basic Law. He said the 12 members - half each from the mainland and Hong Kong - sat together to discuss the issues "like in the Legislative Council". He said there was no voting as the decisions were "collective".

However, he noted: "Hong Kong members don't necessarily hold the same view."

That view highlights the way Hong Kong society looks at political reform. And the man in the middle does have a strong view on whether Hongkongers should accept what is seen as a less than perfect system - take it.

"Who knows whether the path after the first step is for the better? But at least the first step forward means a move towards democracy."

Academic Albert Chen's positions in Hong Kong

Lecturer 1984-88
Senior Lecturer 1988-93
Professor 1993-2007
Chan Professor in Constitutional Law 2007-now
Head, Department of Law 1993-1996
Dean, Faculty of Law 1996-2002

Basic Law Committee member 1997-now
Associate editor,
Author and co-editor of 15 law books