Conservative MSP Liam Kerr could hardly have been more outraged when he learned about the cash Aaron Campbell had supposedly been given to defend himself at trial.

Campbell last year abducted, raped and murdered little Alesha MacPhail on the Isle of Bute. His defence team apparently received £14,000 of taxpayer money to defend a case that seemingly took just £1,300 to prosecute. Mr Kerr raged that “people will see these comparative spends and wonder why vile criminals can access such significant amounts of money”.

He couldn’t have been more wrong, not least because the figures he was commenting on were so clearly incorrect. Eight months of police work comes at a price, as do expert reports. When the cost of transporting witnesses and, quite rightly, accommodating Alesha’s family for the duration of Campbell’s trial are added in, the bill for prosecuting the case will run into tens, if not hundreds, of thousands of pounds.

The cost of defending Campbell too, will be much higher than £14,000, with the bill from lead counsel Brian McConnachie QC alone likely to be closer to £20,000. Then there will be fees for the junior counsel and instructing solicitor, both of whom spent months working on the case but who could not file their claim until sentencing was complete. Add in the cost of procuring and transporting defence witnesses and the bill for the Scottish Legal Aid Board will be significantly higher than £14,000.

Justice, you see, does not - and should not - come cheap. Anyone with even the vaguest understanding of the criminal justice system would have understood that.

But that is almost beside the point given that Mr Kerr’s words display something far worse than apparent ignorance of the price of justice; they display a complete disrespect for the rule of law that would be worrying at the best of times but which is downright contemptible from someone who not only worked as a solicitor before entering politics in 2016 but who serves as the Scottish Conservatives’ justice spokesman too.

It is the mark of a civilised society that every person accused of a crime has the right to have their guilt or innocence determined at trial and even those accused of the very worst crimes - indeed, especially those accused of the very worst crimes - have the right for that trial to be fair. For that to happen they must have access to a competent defence, whose job is not to ensure the guilty are given a free pass but rather that everyone accused of a crime - whether they turn out to be guilty or innocent - is given a fair hearing. That is why legal aid exists.

To argue that every penny spent on defending criminals is a penny wasted, is myopic not just because it undermines that fundamental democratic right but because it risks undermining the entire justice system too.

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Not everyone accused of a crime will turn out to be guilty, but there is no way of knowing that until their trial is over and the money has been spent on their defence. Second guessing that by withholding legal aid from all but those we think or hope are going to end up being exonerated would make a mockery of the justice our court system was designed to deliver. That is also why the cab-rank rule, which compels advocates to take instructions based on their own availability and not on the perceived merits of the case, exists.

Liam Kerr may have been right to say the public doesn’t like criminals having their defence paid for from the public purse, but is it any wonder when people like him use wilful misrepresentation to influence their thinking? Legal commentator the Secret Barrister has written extensively on the problems created when newspaper reports “foment a public association between ‘legal aid’, ‘fat cat lawyers’ and ‘undeserving child murderers’”. Yet that is exactly what Mr Kerr’s words appear to have been designed to do.

That is a dangerous road to go down, not least because without those publicly funded ‘fat cat lawyers’ to conduct their defence ‘undeserving child murderers’ could well find themselves able to walk free in spite of their guilt being proven. That is why it is in all our interests for the very worst criminals to have access to the very best defence. The alternative - that they are released on a technicality because their trial was deemed to have been an unfair one - does not bear thinking about.

There is no doubt that Aaron Campbell, though still a minor himself, is one of the very worst human beings our courts have ever had to deal with. He is, in the words of trial judge Lord Matthews, a “cold, callous, calculating, remorseless and dangerous individual” who attempted to play the system by denying his guilt and implicating an entirely innocent party only to admit everything during a post-trial social work report. Damningly, his defence counsel could find no mitigating circumstances to put forward on his behalf.

But if we allow that boy’s actions to colour our view of how justice should be served we will all lose out, because an attack on legal aid is an attack on democracy itself.