The two cases’ speed disparity has prompted people to ask: what is the relationship between law enforcers and prosecutors, especially at a politically sensitive time?

Who makes the final call on whether to prosecute someone?

The Department of Justice (DOJ) decides on all prosecution decisions in Hong Kong, after reviewing cases from various law enforcement bodies and government departments.

The secretary for justice makes the final call on a prosecution. Under the code, the secretary “is responsible for applying the criminal law, formulating prosecution policy, and superintending the director of public prosecutions and prosecutors in the Prosecutions Division”.

Does the chief executive have any role?

The Hong Kong leader does not and should not have any involvement in prosecution decisions. Chief Executive Carrie Lam Cheng Yuet-ngor has repeatedly said she respects the independence of the justice department’s prosecutorial arm.

But critics say the justice minister’s role is problematic, as he or she, being a cabinet member, could create a perception of possible interference by the administration.

Prominent lawyers and the pro-democracy camp have called for the justice minister to delegate prosecutorial power to the director of public prosecutions. But current justice chief Teresa Cheng Yeuk-wah has rejected that suggestion.

What factors must prosecutors consider when bringing a charge?

The code lays down a number of factors that prosecutors must consider before exercising their duty, including independence, fairness and the public interest.

Before pressing charges, prosecutors should make sure there is a “reasonable prospect of conviction” by considering the evidence. The code also states prosecutors must consider a non-exhaustive list of public-interest factors, including the seriousness of the case, any potential delay, and the age and nature of the suspect, witnesses and victims.

What kind of cases go through the DOJ, and how does it work with other law-enforcement departments?

The justice department provides legal advice to all law enforcement and government departments, such as the police force, the Independent Commission Against Corruption and the Customs and Excise Department.

But for minor offences for which fixed penalties are set, such as illegal parking and littering, the responsible departments can make prosecutorial decisions without first consulting the DOJ.

How does that work when police arrest someone?

After arresting someone, police have to consult the DOJ. In public order cases, such as rioting and unlawful assembly, the DOJ will generally issue written advice and vet the evidence provided by police.

If the prosecutors involved conclude there is “reasonable prospect of conviction”, they can proceed to prosecution.

At that juncture, prosecutors have the option of going ahead with a “holding charge”, a charge brought temporarily to give police time to investigate. The prosecution can later decide to amend or drop the charge, or bring more charges.

How does the justice minister work with the top prosecutor?

Within the justice department, David Leung Cheuk-yin, the director of public prosecutions, heads the prosecution division. He is answerable to the secretary for justice, and advises the minister – and the government as a whole – on criminal matters.

Cheng and her predecessor Rimsky Yuen Kwok-keung, both barristers from civil law backgrounds, have reportedly been involved in various controversial prosecution decisions.

In Cheng’s case that involves charges against the 44 alleged rioters, while in Yeung’s it involves the review of sentences against three young activists including Joshua Wong Chi-fung over 2014’s pro-democracy Occupy protests. While Cheng has said she has the constitutional duty and power to take up such cases, critics have queried her criminal law expertise.