There are thousands of them - and they face being sent to prison for the smallest slip-up. They are people who have been released after serving indeterminate prison sentences for the public protection.
Known as IPPs, the sentences were scrapped in 2012. But the fallout of a tough justice policy - strongly criticised by the Parliamentary Justice Committee last year - continues.
It has left a legacy of prisoners who, even when they have stayed out of trouble for years, can be recalled to jail - sometimes even when they have not committed an offence.
