The chief executive election cannot be considered democratic - even if the entire electorate is allowed to vote freely - if potential candidates are screened out by an undemocratic body, one of the world's leading academics on democracy has said.
Professor Larry Diamond, a senior fellow at Stanford University's Hoover Institution, was speaking amid concern that Beijing will insist on a nomination system that screens out candidates it finds unacceptable for the 2017 race.
Diamond said universal suffrage would be meaningless without a genuine choice between candidates representing alternative points of view. He pointed to the situation in Iran, where universal suffrage exists but candidates are pre-screened by an undemocratic body.
Hongkongers had patiently abided by Beijing's rules in expectation of democracy, which was now threatened by "authoritarian intransigence", he said.
Justice Secretary Rimsky Yuen Kwok-keung had previously dismissed the idea of public and party nomination by saying it contravened the Basic Law. Diamond warned the government against applying a double standard when referencing the miniconstitution.
"If we accept that [the Basic Law] rules out any method [of public nomination] … so it must also be acknowledged that such a [nominating] committee must be 'broadly representative' and must operate 'in accordance with democratic procedures'.
"I do not know how such a broadly representative body can be constituted except … by a democratic election of the people of Hong Kong," Diamond said, adding the committee must not be "grossly over-representative" of elite groups.
Diamond said those opposing democracy in Hong Kong did so out of fear that the "wrong" candidate would win.
The academic also called on pan-democrats and Beijing to start direct negotiations in order to resolve political arguments.
And he warned the legitimacy of the city's government would wither if reform was to fail.
"Hong Kong has waited patiently for democracy under the rules and limits that Beijing has lain down. But there comes a point after which the requirement for 'orderly and gradual progress' becomes a smokescreen for authoritarian intransigence," he said.
Meanwhile, Democratic Party founding chairman Martin Lee Chu-ming praised the reform proposal put forward by HKU law professor Michael Davis - which ignored binding public nomination - as a "litmus test".
"It is very difficult to say the proposal violated the Basic Law," Lee said.
Davis proposed substantially expanding the electoral base of the nominating committee.