The Courts have said, time and again, that the current sentencing options in respect of mentally disordered offenders are inadequate and unsatisfactory.
The latest example comes in the bizarre case of the driver who drove at high speeds against traffic on the AYE in December 2016, causing one death and injuries to several others. It was later revealed that he was suffering from acute psychosis, and had since become compliant with treatment and medication.
In sentencing him 3 years later, Judicial Commissioner Vincent Hoong was concerned with protecting the greater public interest in preventing future recurrences of this episode, but noted that the law did not empower him to make an order mandating periodic medical assessments and review of the offender’s mental health condition in future (PP v Lim Chai Heng  SGHC 272 at ). And so, he meted out an imprisonment sentence of one year, giving primacy to the principle of retribution.
Earlier this year, Chief Justice Sundaresh Menon had noted that the current Mandatory Treatment Order regime precludes offenders who had previously been sentenced to terms of corrective training or preventive detention for offences connected to a previously undiagnosed psychiatric condition (PP v Low Ji Qing  SGHC 174 at ). It would also preclude offenders who had previously served terms of corrective training or preventive detention and only thereafter become afflicted wtih a psychiatric condition.
And as early as 2006, then-Justice V K Rajah had said:-
The current position, where the courts are neither empowered nor endowed with any discretion whatsoever to customise or tailor their sentences in a manner that would be consistent with either the possible recovery or decline of the medical condition of an offender who is unwell, is far from satisfactory. Judges often have to choose between a rock and a hard place when resolving their colliding instincts in determining the appropriate sentence. Should the offender’s medical condition stabilise without any real risk of a relapse it would be quite unjust for him or her to continue to be incarcerated after rehabilitation through medical attention when he or she no longer poses any further risk to the public upon a return to the community. … In order to properly and fairly sentence offenders whose medical condition might potentially be reversed through medical attention and/or with the passage of time, the courts should be conferred the discretion to impose a sentence band with appropriate minimum and maximum sentences tied to periodical medical assessments and reviews. This will minimise the rather unscientific and imprecise conjecture that is now inevitably prevalent when determining appropriate sentences for such offenders. The proposed approach, while fairer to offenders, will also concomitantly serve to address and assuage public interest concerns on adequate sentencing as well as protection from mentally ill offenders with a propensity for violence.
PP v Chee Cheong Hin Constance  2 SLR(R) 707 at .
The question can be put this way. If the courts have accepted that a person had committed an offence because of a mental illness or disorder, then would the public be better served if he were incarcerated for (1) a long period of time; or (2) a shorter period of time (or not at all, in the appropriate case) but with the relevant mandatory orders that he seek treatment so as to reduce the likelihood future recidivism? By all accounts, Mr Lim Chai Heng had suffered from a sudden episode of acute psychosis with no warning signs. The threat of future danger to the public would be much reduced were he to be cured (if that is possible), and not simply locked up.
The Courts want to help us, but are constrained by the current legislation. The inadequacies in our criminal justice system have been quite clearly exposed. Are we going to see change soon?