"CONSENSUAL" stop and search; gun totin' polis appearing on Scottish streets; criminalisation of "offensive" songs at football matches, "super" identity cards.

You could be forgiven for thinking that Scotland is turning ever so slowly into a police state.

Of course, we still have the rule of law in Scotland and citizens cannot, on the whole, be banged up at random, unless they are terrorist suspects. Nor are our police on the whole corrupt, politicised or aligned with organised crime.

But never mind. The price of freedom is eternal vigilance and there is no doubt that something very strange has been happening in Scotland since the creation two years ago of the new Scotland-wide super-force, Police Scotland, led by its attention-seeking Chief Constable Sir Stephen House. Last week's confusion over the continuation of "consensual" stop and search suggested a force that is either too big, out of control or both.

The change in police culture began almost immediately the eight regional forces were amalgamated in February 2013. Police started, to put it bluntly, throwing their weight around. The late Margo Macdonald MSP was dismayed when police raided Edinburgh's genteel back-street saunas trying to have their places of work shut down. She'd been campaigning for years to get prostitutes off the streets, but here they were being forced out again into the underworld of organised crime and trafficking.

Then, police constables suddenly started appearing randomly on streets in Glasgow and Inverness armed with guns. Not to combat armed gangs or apprehend terrorist suspects or but at routine crowd control and traffic incidents. Last week it emerged that police in Scotland are still searching children under 12 despite having agreed to curb the practice.

This whole practice of "consensual" stop and search, which is now to be outlawed, is as inexplicable as it is disturbing. The Sunday Herald revealed that 600,000 searches were conducted in Scotland last year alone, only 70% of them with any legal justification. Scottish citizens were nine times more likely to be frisked than people living in New York.

The police claim that search is necessary to apprehend knife-carrying criminals, but as the Sunday Herald also revealed, Police Scotland over-estimated the numbers of weapons seized by 40%. Stephen House admitted last week that their statistics on stop and search as a whole were "unreliable".

This does not inspire confidence. Our police walk the streets in our cities with an ominous swagger, clad in sinister black, tooled up with stab vests, handcuffs and CS sprays. The way the police display themselves tells you a lot about their attitudes. They don't seem to understand why it is wrong to detain people for searches without legal justification.

And they clearly feel that elected politicians should not be trampling on their manor. The Scottish Police Federation issued an angry rebuke to parliamentarians last week for interfering with their right to stop and search citizens at will. Someone should remind them that Parliament makes the law; police are there to enforce it

But politicians only have themselves to blame here. The Scottish Government has created a monster in Police Scotland and seems to have a tin ear when it comes to civil liberties. The root of the problem is that politicians love to ban things - to show they can be tough on knife-carrying yobs, drink-drivers, sectarianism, domestic violence and rape.

The police like all this banning of stuff because it increases their role in enforcement. The polis have become particularly adept at allying with victims' groups, churches and populist politicians in extending the reach of the criminal law and giving them greater scope for intervening in people's lives.

More and more ordinary citizens are finding themselves in jeopardy of the law. With the A9 being covered with speed cameras, just about anyone who overtakes a lorry is an offender. The penalties for driving with more than the new limit of 50mg in the blood in Scotland are draconian compared with countries like France or Australia.

The police are happy to support politicians introducing unworkable and illiberal measures such as the Offensive Behaviour at Football Act for similar reasons. You can now be banged up for singing certain songs in a pub just because football is on the TV.

The attempt to abolish the centuries-old requirement of corroboration in criminal cases is another area in which the police were keen to back up a politician trying to "do something". The former Justice Secretary, Kenny MacAskill, was responding to complaints from women's groups about the lack of prosecutions in rape cases.

But the proposed solution, skewing the justice system in favour of prosecution and threatening to undermine the presumption of innocence, was a response too far, and has been shelved. The police favoured the abolition of corroboration for the obvious reason that they would no longer have to go to the bother of presenting credible evidence in court.

The paradoxical problem for the police is that crime is actually going out of fashion. All aspects of crime are down, significantly so, even violent crime and knife-carrying. When did you last hear of a big bank robbery?

Murder is so infrequent - despite the dominance of Nordic noir on our screens - that it's becoming an endangered species of criminal activity. There were only 61 in Scotland last year, down by half in a decade, and of course most murders are crimes of passion or drink-related and easily solved. This isn't the USA where every evening news bulletin is a manslaughter horror-show.

But less crime means the police have to work harder to justify their existence. They are not getting the publicity they need to argue the toss with politicians wanting to cut budgets. Popular media generate expectations of the police collaring criminals, putting drugs on tables, seizing guns, pursuing serial killers. But most crime is now happening anonymously on the internet.

The Scottish Liberal Democrats have been fighting a lone battle against the erosion of civil liberties by the police and the Scottish Government. They get precious little reward for it, but we should be glad that someone still cares about this stuff.

The LibDems' latest campaign is against the setting up of what appears to be an electronic identity database of precisely the kind that was rejected by the Scottish Parliament in 2010 when Tony Blair was pressing for the introduction of identity cards. We don't want Police Scotland turning into Big Brother.

Politicians need to be saved from themselves by a vigilant public and a robust parliamentary opposition. Unfortunately in a Scottish Parliament in which the SNP dominate the chamber and committees, and there is no revising chamber, there is a problem of holding the executive to account.

Nicola Sturgeon has shown over stop and search that she is prepared to be tougher than her predecessor in dealing with Police Scotland. The First Minister appears to be less prone to using the law to send political messages on issues like sectarianism - though the abolition of automatic early release of prisoners perhaps indicates that she is not wholly averse to the false belief that "prison works".

She needs to curb the enthusiasm of her ministers for banning stuff and trying to regulate our personal space. She needs to avoid being captured by victims' groups and single-issue pressure groups. And she need to conduct a review of Police Scotland. The road to hell is paved with good intentions, and that applies in Scotland as well as Westminster.