Sex offenders in some areas will be forced to take lie detector tests to see if they are still a danger to the public, the Ministry of Justice has said.
A pilot scheme will run from next April for three years. Under an earlier, voluntary pilot, nearly 80% of tests prompted admissions.
But fewer than half of those eligible for the tests agreed to be tested. Under the new pilot, paedophiles and other offenders will have no choice.
They will be asked questions while their heart rate, sweating, brain activity and blood pressure are monitored.
The results will be used to check if they are a still a danger to the public and could result in changes to how they are supervised.
But information that comes out during the tests, which last around 90 minutes, cannot be used as evidence.
A consultation document on the rules of the programme was published by the Ministry of Justice.
The pilots are likely to be held in the East and West Midlands, the Ministry of Justice said.
If successful, the scheme could be extended across the country.
