Here is an informed expert analysis by Associate Dean Simon Young of the HKU Faculty of Law. He said that I can make it available to interested parties.
Under our anti-money laundering laws, the police have a wide power to effectively freeze funds in bank accounts by writing a letter to the bank. The letter will normally state the police reasonably suspect the funds to be proceeds of an indictable offence and, unless the police grant the bank consent, the bank may be guilty of money laundering if they allow the customer to deal with the funds. This effectively freezes the funds and the bank cannot tell the customer why (as there is a tipping off offence in the legislation). One might think this is a police power that could be abused especially since there is also a power for prosecutors to apply to a court to restrain property reasonably believed to be proceeds of crime. However, our Court of Appeal has upheld the constitutionality of this ‘no consent’ police power so long as it applies only during the investigatory stage, which must proceed without unreasonable delay and only on the basis of reasonable suspicion. Here is the link to the decision: https://www.hklii.org/eng/hk/cases/hkca/2019/70.html