Explainer: What is the Certificate of Substantive Assistance?

It is a Certificate issued by the Public Prosecutor verifying that the accused has substantively assisted the Central Narcotics Bureau in disrupting drug trafficking activities within and/or outside Singapore. If such a Certificate is granted to an accused person who is also found to have merely been a courier, the court can then exercise its discretion to impose life imprisonment and caning instead of the mandatory death penalty.

Notably, the legislation makes clear in s. 33B(4) that the Certification decision is at the “sole discretion” of the Public Prosecutor. The discretion is not subject to judicial review, unless one can prove to the court that there was bad faith or malice.

When and why was this introduced?

Before 2012, the death penalty was mandatory for those caught trafficking controlled drugs above the amount stated in the Second Schedule of the  Misuse of Drugs Act. (For example, 15g and above of heroin.)

In 2012, the Singapore government reviewed the mandatory death penalty. While the government maintained the death penalty remains an “effective deterrent and an appropriate punishment for very serious offences”, it claimed that the certificate system would give drug couriers an additional incentive to provide information that would allow CNB to tackle drug syndicates and networks. 

The Use of the Certificate of Substantive Assistance

An analysis by Amnesty International found that between 1 Jan 2013 (when the certificate system came into force) and 30 Sep 2017, there was an overall decline in the number of new death sentences imposed. Out of 66 capital offences related to drug trafficking, 34 had the mandatory death penalty imposed while 32 met the requirements under s. 33B for discretionary sentencing by the Courts. None of the 32 were sentenced to the death penalty. 

In response to a parliamentary question in 2016, Minister of Law K. Shanmugan highlighted that information provided by drug couriers have contributed to the arrest of more than 80 drug traffickers. However, no further information was provided that allowed the comparison of these figures with the period before the inception of the Certificate system, nor comparing against arrests not made via investigative leads from drug couriers.  

Issues with the Certificate System

Since the inception of the Certificate system, the courts and the involved parties have had to grapple with significant legal issues. 

  1. The extent to which a decision to issue a Certificate is subject to judicial review  

Under s. 33B(4) of the Act, the issuance of the certificate is by the “sole discretion” of the Public Prosecutor, and prevents any action or proceeding against the Public Prosecutor “unless it is proved to the court that the determination was done in bad faith or with malice.” 

In the case of Muhammad Ridzuan bin Mohd Ali v AG, the prosecutor granted the co-accused but not the applicant the Certificate of Substantive Assistance, despite both of them being involved in the same criminal offense. The court had declared both of them to be ‘couriers’ within the definition of s. 33B(2)(a). The court dismissed an application for judicial review on the grounds of bad faith, citing a lack of evidence that there was arbitrary discrimination against the applicant, but left the question open as to whether s. 33B(4) prevented the Court from reviewing the Certification decision.

The position in law was later clarified in Nagaenthran v AG a/l K Dharmalingam v PP, where the Court opined that s. 33B(4) did not have the effect of  “ousting the power of the courts to review the legality as opposed to the merits of the PP’s determination under s 33B(2)(b).” In other words, it would be possible to bring action against the PP on the usual judicial review grounds of illegality, irrationality and procedural impropriety – for example, if the Public Prosecutor made the Certification decision based on factors irrelevant to whether ‘substantive assistance’ was provided to the CNB.

In practice, it is difficult for any accused to seek review of the Public Prosecutor’s decision. The burden of providing preliminary evidence that the PP has made an illegal decision lies with the applicant. This must be done before the applicant can proceed to actual judicial review. 

Yet the Public Prosecutor has no legal obligation to disclose the reasons for not issuing a Certificate (and no legal obligation to disclose reasons for determining or discontinuing a charge), and has indeed chosen not to do so in many cases, leaving the accused with limited information with which to make their challenge. A common theme in cases where such applications are filed is that the reasons provided by the applicant are dismissed as “speculative”, or lacking in evidence.

Further, the extent to which the Public Prosecutor’s decision can be reviewed by the courts is a matter of the separation of powers between the Judiciary and Executive arms of the state. While the Public Prosecutor has a role in assisting the court in making sentencing decisions, it is accepted principle that it is ultimately for the court to decide sentencing. While it might legitimately be the case that the Certificate system is an area of decision making where the PP is in a better position to make judgements, the effective result is, as one academic commentator pointed out, that the Public Prosecutor has de facto control of sentencing in mandatory death penalty cases via s. 33B(4). In practice, there has not been a case where the Court imposed the death penalty on an accused issued with the Certificate. 

  1. ‘Substantive assistance’ is an unfair standard to determine someone’s life or death.

The MDA itself is deliberately unclear on what counts as ‘substantive assistance’, only defining it as the provision of information leading to the arrest or detention or prosecution of any person involved in any drug activity. In the parliamentary discussion leading up to enactment of the Certificate system, the Minister of Law argued that a clear definition would weaken the deterrent effect of the death penalty. The argument was also put forth by the Minister of Law given that the goal of the system was to incentivise drug couriers to provide information, rather than as a means for couriers to avoid the death penalty.

As the court in Prabagaran a/l Srivijayan v PP points out, the matter of substantive assistance is a ‘multi-faceted inquiry’: “taking into account a multitude of factors such as the upstream and downstream effects of any information provided, the operational value of any information provided to existing intelligence, and the veracity of any information provided when counterchecked against other intelligence sources.” 

But precisely because of its multifaceted nature, most of these factors are not within the control of the drug courier. A fully cooperative accused may indeed provide information to the CNB, but the accused has no control over where or how CNB uses or chooses not to use the information provided. In making Certification decisions, the Public Prosecutor does not consider the truthfulness of the accused or whether the accused has provided information in good faith. From the point of view of the accused, whether or not they receive a certificate might as well be a lottery. ‘Substantive assistance’ fails to reflect the moral culpability of the accused. 

  1. The Certificate system could potentially lead to wrongful convictions.

Our previous explainer highlighted the potential for wrongful convictions that partly arises from the Certificate system, as an accused may be incentivised to incriminate a co-accused in order to receive a Certificate. But it is also possible that an innocent accused person might choose to admit to being a courier so as to avoid the mandatory death sentence.

As SMU law professor Chen Siyuan points out, the risk of this occurring is amplified by other unique features of the Singapore system, including the presumptions under s17 and s18 of the MDA that anyone found with controlled drugs is presumed to be in possession of them, and if above a certain amount, is presumed to possess them for the purpose of trafficking. An accused must rebut these presumptions on the balance of probabilities. Facing an uphill task in proving their innocence, an accused might believe that they stand a better chance admitting to being a ‘courier’ than denying the charges laid before them. This is also affected by the fact that the Court could draw adverse inferences from an individual remaining silent during the investigation process, and the possibility of denial of legal counsel at the early stage of the investigation.

TJC is concerned that the Certificate system creates potential for the arbitrary exercise of the death penalty. It leaves the power to determine life and death in the hands of the Public Prosecutor instead of the courts. This is all the more worrying in the absence of sufficient transparency along with independent checks on the exercise of prosecutorial powers, in a legal system where the Prosecutor already has extensive discretionary powers. It has long been the position of the AGC not to disclose its prosecutorial guidelines, citing concerns of increasing litigation and that publishing specific guidelines would circumscribe prosecutorial discretion. 

Ultimately, the main flaw of the Certificate system is that it places matters of life and death in service of strictly utilitarian purposes. It fails to consider the social or structural circumstances that lead an individual to become drug courier, and the moral culpability of the individual. While a criminal legal system may consider utilitarian or practical purposes in its design, it should not do so in a manner which undermines principles of fairness and justice, or come at the cost of the fundamental rights of individuals undergoing the criminal legal process.


  1. S. 33B Misuse of Drugs Act
  2. ‘Misuse of Drugs (Amendment) Bill’ https://sprs.parl.gov.sg/search/topic?reportid=021_19790921_S0002_T0008
  3. ‘Drug Traffickers Arrested in Singapore through the Certification of Cooperation Framework’, https://sprs.parl.gov.sg/search/sprs3topic?reportid=written-answer-3075 
  4. Muhammad Ridzuan bin Mohd Ali v AG [2015]
  5. Nagaenthran a/l K Dharmalingam v PP and another appeal [2019] SGCA 37
  6. Prabagaran a/l Srivijayan v PP [2017]
  7. Chen Siyuan (2016) The Discretionary Death Penalty for Drug Couriers in Singapore: Four Challenges, 20 INT’l J. EVIDENCE & PROOF 49.
  8. Kumaralingam Amirthalingam (2018) The public prosecutor and sentencing: drug trafficking and the death penalty in Singapore, Oxford University Commonwealth Law Journal, 18:1, 46-72,
  9. Kumaralingam Amirthalingam (2013) Prosecutorial Discretion and Sentencing Guidelines, Singapore Journal of Legal Studies, 50-75
  10. Amnesty International (2017) Cooperate of Die: Singapore’s Flawed Reforms to the Mandatory Death Penalty

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