John Cooper argues that by implementing cost-cutting acts, the Government is in danger of repeating the mistakes of the past. John Cooper is a barrister at 3 Gray's Inn Square.

We all know that the primary purpose of any new government act in relation to the criminal justice system is to save money. But based on past experience, the opposite is usually achieved.

The last administration considerably undermined a defendant's right to silence with the introduction of a judges' duty to inform the jury of their option to draw "an adverse inference" on a defendant's failure to give evidence.

In a criminal trial the jury is told that should it be satisfied that the only explanation for a defendant's failure to mention important facts which were subsequently to be relied upon in evidence is that the evidence is a recent fabrication – and if the only sensible explanation of the failure to mention it is that it is a recent fabrication – then the jury can properly draw the inference against the accused – the adverse inference, be it based on silence in interview or failure to give evidence.

As a result of the changes police have had to learn an entirely new caution and vindictive defence barristers now often ask the police to repeat the words of the new caution in front of the jury to see how many get it wrong. "The court will infer something if you do not give evidence" is an attempt that sticks in my mind.

There is a discretion, exceptionally exercised, not to direct the jury of its power to draw an adverse inference. Each case will be determined upon its own facts, there is no hard and fast procedure, but if, for instance, a defendant is of very low intelligence, the judge should decide whether an adverse inference should be drawn.

The categories of exception are open and though the court will only exercise its discretion very sparingly the boundaries are often being tested.

What this means is that the Crown Court will have to decide, based on the oral evidence of the defence and prosecution psychologists and psychiatrists, whether the particular defendant is of such an intellectual disadvantage that their silence in the dock could not be held against them.

Often these hearings take two full days of evidence and legal argument.

Before the introduction of this legislation, if a defendant failed to give evidence, the matter would be dealt with in the time it took a judge to say to the jury "that was his right and it should not be held against him".

It does not take a forensic accountant to quantify the varying costs to the public purse between a two day hearing and a 10-second direction.

As the current government tries for a second time to reduce a citizen's right to jury trial, criminal lawyers wait with eager anticipation at the increased opportunities which will be presented to appeal magistrates' decisions not to commit to the Crown Court.

This exciting opportunity for criminal practitioners will make the increased cost of the reduction of the right to silence a mere bagatelle compared to the money spinner presented by Jack Straw's jury bill.

In addition, criminal lawyers are further enthused by Lord Bingham's observations that it is possible that the silence provisions could lead to hostile findings under the European Convention unless they are the subject of carefully framed directions to juries.

Criminal lawyers have never had it so good!