He engaged in vigorous debate with the three Court of Appeal judges who took turns to query the arguments he presented in seeking a life term for a woman who plotted with her teen lover to kill her husband.

The three judges, Chief Justice Chan Sek Keong and Judges of Appeal V. K. Rajah and Andrew Phang, reserved judgment.

Over 50 lawyers packed the public gallery to see the first Attorney-General in over a decade to argue in court.

Prof Woon mounted several arguments in urging the court to up Aniza Essa's jail term from nine years to life.

He made a radical call to 'bury' established sentencing guidelines used by judges in deciding when an offender should be jailed for life.

CJ Chan and Justice Rajah suggested that Prof Woon may be arguing a moot point.

In the past, judges in culpable homicide cases had to decide whether to impose jail terms of up to 10 years or life. Because of the big gulf between the two possible sentences, the criteria set out in the English judgment 41 years ago helped judges to determine when a life sentence was appropriate.

The law was changed in April with the 10-year ceiling raised to 20, thus reducing the gap. But Prof Woon asked that the court make it clear that the criteria is not 'iron-clad'.

CJ Chan also noted that aside from the intellectual aspect, he was looking at the 'practical side'.

'Is she (Aniza) a person who will re-offend? If there is a likelihood that she will not re-offend, is it justified to send her away for a minimum of 20 years?'

Life sentences here run for at least 20 years before a convict is eligible for release.

Prof Woon then argued that defence lawyers should be made to prove the claims made in their clients' mitigation plea for leniency.

He noted that Aniza painted herself to be an abused wife and suicidal, and the trial judge was 'a little too indulgent' in considering these in deciding the sentence.

Prof Woon also pointed out the disparity between the sentence of the teenager, who has been indefinitely detained, and that of Aniza, who could be out in six years for good behaviour.

Aniza was ill enough to avoid a capital charge, but the fact that she had told the boy to delete incriminating SMS messages from his phone showed her scheming mind.

Saying most people would find the disparity 'not just', Prof Woon noted: 'The boy is in jail for life. It boggles the mind that she should be out in six. The disparity is so huge.'

He pointed out that Aniza was no 'leaf in the stream' being swept along, but had egged the boy on to kill her husband after he lost his nerve on the first two tries.

Prof Woon also urged a heavier sentence for a deterrent effect.

But Justice Rajah pointed out: 'We don't make examples of mentally ill people to deter other people.'

Aniza's lawyer Noor Marican also said it was unfair to compare the two convicted persons because there were psychiatric reports explaining his client's mental state.

Mr Marican took 15 minutes to make his arguments, saying he will not add to the 'intellectual' discussion.

selinal@sph.com.sg