Prisoners who have taken jobs outside jail are to find out the result of their High Court claim that a levy on their wages which goes to victim support is too high. The test case action affects inmates working in the community as they prepare for their release and to “go straight”.

A judge in London is to announce his decision in the challenge against the legality of the way Justice Secretary Ken Clarke is operating rules governing deductions from pay packets.

Under the Prisoners’ Earnings Act 1996, inmates engaged in “enhanced wages work” outside prison have 40% of pay that is in excess of £20 paid to victim support.

Kate Markus, appearing at a recent hearing with Hugh Southey QC for several working prisoners who cannot be named, told Mr Justice Sales that the payments were “disproportionate” and there was “widespread concern” about the levy.

She referred to the pressure group “Unlock” (the National Association of Reformed Offenders) which argues that the levy is undermining rehabilitation and acting as “a disincentive to work”.

Mr Clarke could, and should, have allocated a portion of the 40% levy to help the inmates rebuild their lives as well as help victims, she argued.

Ms Markus asked the court to declare that the way Prison Service rules were being applied to inmate’s earnings was “incompatible” with the European Convention on Human Rights.

She said Mr Clarke had failed to strike a balance between the interests of victims of crime and inmates.

The case mostly affects the inmates of open prisons but also some Category C prisoners allowed to work out in the community on day release under contracts of employment.

Rates of pay from outside employers are higher than those for work performed in prison.

The court heard claims that prisoners with high travel expenses to reach work were being left with no wages.

There were also complaints that they were being left with insufficient funds to pay towards costs of resettlement such as helping out with family expenses, or saving for a rent deposit and furniture for when they were released.

Mark Leech, editor of Converse the national newspaper for prisoners and the founder of UNLOCK said: “This levy is nothing more than a political tool to win votes by attacking those prisoners who have complied with everything they have been asked to do, have achieved trusted positions in open prison conditions, are nearing the end of their sentences and who are preparing for their release.

“If Ken Clarke is serious about wanting to help victims of crime then he should place the levy on all of the 85,000 people in prison, and not just the handful of inmates who this disingenuous provision unfairly targets.”