Two youths who wanted to be jailed were instead sentenced to reformative training.
They had impersonated Central Narcotics Bureau officers, detained a man under an arrest threat and made him pay $8,000 for release.
District Judge Lim Keng Yeow rejected their plea to be jailed, ruling that they could do with the minimum 18 months' detention at the Reformative Training Centre (RTC). It was flawed thinking to treat a day in jail and a day at the RTC as equal, he said.
Calling the offences "not trivial in any way", the judge said that the cheating carried out by pretending to be CNB officers was compounded by grave threats, large sums of money and "a long period of nine hours during which the victim was kept in fear".
The offenders also showed "little or no remorse", the district judge said, in decision grounds issued on Thursday.
Don Mark Ricto Fernandez and Phil Ng Wei Long, both 20, had initially claimed trial, but U-turned and pleaded guilty after the victim was cross-examined in court.
Last year, the two men colluded with one Ryan Tan in posing as CNB officers, with Ng helping Tan to threaten the victim with arrest for alleged drug offences unless he paid them $16,000.
After the threat was made, Ng remained with the victim in the Tanjong Pagar area for several hours, from around 10.30pm, while the victim waited for a friend to transfer money to his bank account.
At about 3am, Ng, Tan and the victim took a cab to Lower Peirce Reservoir to wait until the man could withdraw more money at a bank branch counter in the morning. Tan took $2,000 from the man at the reservoir.
The victim was then taken to Thomson Plaza, where he withdrew $6,000 and gave it to Tan.
He was finally set free after more than nine hours.
The court heard that both offenders gave "active and strong support" to Tan, who has already been sentenced to reformative training.
The duo's lawyer, Mr K. Jayakumar Naidu, argued that they should be sent to jail to ensure parity with the sentence given to Tan, who played a leading role and had other serious offences under his belt.
The district judge disagreed, saying that the predominant concern is youth reform as both offenders were under the age of 21.
He said that although Tan was charged with more serious offences, it did not follow that Fernandez and Ng should not be sentenced to reformative training. That would overemphasise the principle of parity and "completely disregard or misapprehend the rehabilitative framework" set in place for youthful offenders.
While the minimum reformative training term is longer than any jail term in this case, the duration "by itself" would not prevent imposing reformative training, said the judge.