OPPOSITION politicians have criticised proposals to allow judges and juries to hear the previous convictions of an accused, warning it could undermine impartiality and justice.

Their concerns follow warnings from senior advocates that the change would lead to "horrific miscarriages of justice".

The Herald reported yesterday that a draft bill from the Law Commission concluded the current rules for evidence, which prohibit the sharing of information about any similar convictions of the accused, are "illogical and arbitrary".

But Patrick Harvie MSP, co-convener of the Scottish Green Party, said: "There's a real danger that this proposal will lead to miscarriages of justice.

"It's important to remember that convicting the wrong person for a crime is even worse than letting the guilty go free – it's a double injustice, with the innocent ending up in prison and the guilty still at large."

Liberal Democrat justice spokeswoman Alison McInnes MSP also raised concerns. She said: "The presumption of innocence is the keystone of our justice system.

"Stating prior convictions or referring to bad character may mar the fair and proper legal process we have in Scotland. These proposals, taken together with Lord Carloway's recommendations on ending the need for corroboration, could really call into question the impartiality of our justice system."

Ministers asked the Law Commission to reconsider the admission of previous convictions following the collapse of the World's End trial in 2007. Angus Sinclair had been accused of the murders of Christine Eadie and Helen Scott in 1977.

Under the new proposals the admission of previous convictions would depend on their relevance to the case in question rather than the discretion of the judge, and would be challengeable by the defence.

Serial killer Peter Tobin's murder of Polish student Angelika Kluk could not be made public at his trial for the murder of Vicky Hamilton. However, a jury in England took 13 minutes to find Tobin guilty of the murder of schoolgirl Dinah McNicol. They were told of his previous offences at the start of the trial.

The draft bill is now being considered by ministers.