Join a secret society and face the possibility of being thrown into jail without trial under the Criminal Law (Temporary Provisions) Act.

The potent and sometimes controversial law was introduced close to 60 years ago, but is still something whispered among the ranks of secret societies and gangs in Singapore, according to a former member.

Benjamin (not his real name) was just 18 when he was detained under the Act for his involvement in a secret society. Now a 26-year-old undergraduate, he spent four years behind bars for his frequent participation in gang fights, riots and other secret society-related crimes.

"The other gang members had talked about (the law) before, but at 18, I did not expect to be detained under it," he said.

The Criminal Law (Temporary Provisions) Act was enforced in 1955 when organised crime, especially secret societies and gangsterism, was rife in Singapore. It has served as a potent weapon against serious crimes that threaten public safety, peace and good order, said the Ministry of Home Affairs (MHA).

A Bill passed in Parliament yesterday will extend the lifespan of the Act for another five years starting Oct 21 next year. The changes will also prescribe a list of specific offences within the Act's ambit.

While Benjamin declined to share the specifics of his gang activity, the MHA said the Act is used as a "last resort" to issue detentions and police supervision orders against people engaging in crimes that threaten society, peace and good order.

Prosecuting offenders in court is the preferred course of action, said the ministry. The Act is used in instances when court prosecution is not possible, because accomplices and witnesses are unwilling to testify in court for fear of reprisals.

Sharing his experience of detention, Benjamin said: "For the first few days, I was shocked. I felt confused and lost and I did not know when I could go back to my family."

But he said it was a wake-up call that made him want to "do something" with his life. So when the chance to study came, he signed up for it. During his four years of detention, Benjamin completed both his O-and A-level examinations.

"I spent the first year praying to get out of prison. But during the second and third years, I did not think so much about it because I wanted to pursue and concentrate on my studies. If I were out of prison, I don't think there would have been such an opportunity."

In 2015, Benjamin was released from detention after completing his A levels in prison.

For a year, he had to fulfil police supervision orders where he was restricted from visiting high-risk areas, such as entertainment outlets, and had to adhere to strict 7pm curfews. He also had to check in weekly with the police.

Thinking back to his days in prison, Benjamin said: "At first, I was very angry and sad to be detained. But without this detention, I don't think I would be studying today. Maybe I would not even be alive."