“The Department of Justice made the decision according to its professional opinion. The matter can only be explained by the secretary for justice.”

It said the department had decided there was “insufficient evidence to support a reasonable prospect of conviction” for any criminal offence.

Justice officials ‘should have got second opinion’ in clearing CY Leung

The department has not explained the legal principle behind its decision and why Leung’s payment by UGL did not contribute to a conflict of interest.

A department spokesman said Cheng was on leave until December 26.

While acknowledging public concern, Benjamin Tang Kwok-bun, chairman of the ICAC’s operations review committee, which oversees investigations, said members were satisfied the agency had pursued the case in an impartial manner and without fear or favour.

He said the committee endorsed the decision for the ICAC to take no further action.

Tang said the case was discussed in detail at eight meetings annually from when the file was opened in October 2014, and that members raised many questions.

“We respect the legal advice the secretary for justice gave us. Our main duty is to monitor whether graft investigators tried their best on the case, which I believe they did,” Tang said. “It has to be left to the secretary for justice to explain her legal advice to ease everyone’s worries.”

Pan-democratic lawmakers will stage a march on Sunday afternoon to Cheng’s office and call on her to explain the decision, saying that to not do so risks denting public faith in the anti-corruption regime.

“All we got from the justice department so far was this one-page press release – just barely one page,” said Democratic Party lawmaker Lam Cheuk-ting, holding the statement.

“If her department is still dodging questions from the public, one would question whether she is fit to be in office.”

Acting chief executive Matthew Cheung Kin-chung, however, called the statement “detailed”, and said the department would only respond to public concerns at the right time.

“The Department of Justice clearly explained there was insufficient evidence,” Cheung said on Tuesday morning ahead of a regular cabinet meeting. “Whether to disclose more information is the department’s own call.”

Legal scholars have questioned the decision. Activist Kwok Cheuk-kin lodged a judicial review seeking to overturn director of public prosecutions David Leung Cheuk-yin’s decision not to prosecute Leung.

Since 2014, the ICAC had been investigating the payment to Leung, who was the city’s leader from July 2012 to June 30, 2017.

Democrats consider next move after CY Leung investigation ends

The controversy stemmed from a deal Leung struck following UGL’s 2011 purchase of DTZ, a property services company once listed in Britain, of which he was a director. As part of the deal, Leung agreed not to form or join a rival firm and to help promote the company.

Leung received part of the sum after becoming leader in 2012. But he did not declare this during a meeting with his cabinet, the Executive Council, sparking concerns over a possible conflict of interest.

Criminal law scholar Simon Young of the University of Hong Kong said the justice department might have seen the UGL payment as legitimate.

He said Leung’s deal was different from the case of disgraced former No 2 official Rafael Hui Si-yan, who was sentenced to 7½ years in jail for pocketing almost HK$19.7 million in bribes in an agreement he made before he rejoined the government.

“It was misconduct for Hui to agree to be put in such a position without making an appropriate conflict of interest disclosure,” Young said.

“With Leung I don’t think there is evidence that receiving the UGL payments would dispose him to favour UGL while in office since the payments were for specific reasons related to his affairs before he assumed office.”