W hen I lived in a so-called tolerance zone in Leith, I realised the limits of my liberalism.

Prostitutes as thin as whippets would shiver on a late-night street, before disappearing into unlit shop doorways and car-parks with their clients. From my flat you'd see them talking to men in cars, or chatting to each other, fag ends glowing in the dark. Their pimps would park their 4x4s outside my door, burly shadows behind tinted glass, as they kept an eye on their girls.

Some hailed this red-light experiment as a triumph of commonsense. To me, it solved nothing, and made the district less safe for everyone. Seeing girls stationed beneath the lamps on Salamander Street was to think of fish in a barrel, but easier to pick off. Nor was it unusual to watch a car crawl past a young woman on the nearby streets, the driver rolling down the window as he tried to decide if she was on the game, or merely a skimpily-dressed schoolgirl.

Following public outcry, this experiment was short-lived. With rare exceptions such as that, however, Edinburgh's sex trade has for decades operated in a fairly enlightened way. The council's policy of licensing saunas and massage parlours where prostitutes are reputed to work has effectively contained and sanitised the business, taking women off the streets and offering them a degree of safety and comfort their free-range sisters will never know.

The first hint that things were about to change came a few months ago when the licensing of certain well-known Edinburgh properties was challenged. Then, as revealed in Saturday's Herald, came concerted police raids in the capital and Fife last week, in which a handful of individuals were charged with drug offences, sex workers and customers were interviewed, and investigations into sexual abuse begun.

This was the first significant salvo of the unified Scottish police force, Police Scotland, which came into operation on April 1. It suggests a serious, uncompromising flexing of muscles, and it also promises trouble ahead. In ignoring Edinburgh City Council's principle of tacitly turning a blind eye to brothels, the Chief Constable of Police Scotland has rendered the council's decisions null, and its citizens' ballot papers void. By over-riding the lenient policy of a democratically elected council, Police Scotland has made it plain that in future a single standard will be applied uniformly across the country. We must therefore assume that voters' wishes are now irrelevant if they do not conform to this rigid nationwide directive.

No-one can deny the benefits of a single police force. If the NYPD and London Met can cover cities of eight million citizens, then a unified body can certainly handle our 5.2 million. The Edinburgh sauna raids, however, have highlighted the tensions inherent in imposing a single system on a country of wildly varying political, social and religious beliefs.

It seems reasonable to infer that the new one-size-fits-all system for the sex trade will be more akin to Glasgow Council's zero tolerance policy than the capital's laissez-faire position. Aberdeen City Council, which takes an equally liberal line to Edinburgh on prostitution, should perhaps brace itself for similar scenes.

In certain company, not to condemn prostitution outright is like confessing a heroin addiction. Few subjects are more divisive. Idealists want the sex trade driven out of business. What reasonable person wouldn't? But prostitution, like giant hogweed and cockroaches, will be flourishing long after all of us are gone. Since we cannot eradicate it, we can only hope to contain it, as humanely as possible.

Those who condemn Edinburgh City Council's open-minded attitude might be less judgmental if they knew that in Glasgow, where most prostitutes operate on the streets, the number of sex workers raped and murdered is dramatically higher than in Edinburgh. That fact alone, to my mind, justifies blurring the legal edges and quietly condoning discreetly-run brothels.

Indeed, it's worth asking if it would not be preferable to legalise brothels and openly regulate the trade. That way not only would prostitutes be less vulnerable and open to abuse, but so would their punters. To judge by Police Scotland's clampdown, however, the possibility of such a liberal discussion lies in the realms of fantasy – but sadly not the sort a dodgy masseuse can satisfy.