It is not the section of the Criminal Justice and Immigration Act 2008 defining the nature, and legality, of extreme pornography that is unreasonable. In the case of the barrister Simon Walsh, it was the Crown Prosecution Service's application of the law that was at fault.

The jury's decision yesterday to acquit Mr Walsh on charges concerning photographs of him engaging in consensual, legal sexual activity is, therefore, to be warmly welcomed. In his summing up, the Judge told the jury: "It is emphatically not your duty to send out a message about modern society." Neither is it the duty of the CPS.

Mr Walsh's case is not only important because it raises questions about the right of the state to intrude on the privacy of the individual. It also illuminates, once again, the failure of those in authority to distinguish between the letter and spirit of the law.

The inappropriate prosecution of Mr Walsh was not a one-off. The same troubling attitude was on display in what became known at the Twitter Joke Trial, when a car parts company worker tweeted an exasperated mock threat to blow up Doncaster airport when it was closed because of snow.

It was obvious to Paul Chambers' handful of followers that he was joking. But the CPS pursued the case to the bitter end, despite widespread condemnation of its heavy-handedness, and only after a two-year legal battle was Mr Chambers' conviction was finally quashed in July.

And then there is the ruling that Bob Ashford – who has been director of strategy for the Youth Justice Board for the past 10 years – is ineligible to stand for election as a Police Commissioner because, more than four decades ago, he joined a group of boys shooting at cans with an air rifle near a railway line. The decision is a travesty of nit-picking, turning away a promising candidate for public office over a triviality.

Such legal pedantry is an affront to those whose lives are up-ended by it. And it does untold damage to public respect for the law. It is time for a bit more common sense.