Like a cat playing with a ball of wool, the longer politicians and interested parties spend trying to tease out the provisions of the Offensive Behaviour at Football and Threatening Communications (Scotland) Act, the more confused and knotted it becomes.

After the disgraceful incidents aimed at Celtic manager Neil Lennon and others, the Roman Catholic Church in Scotland supported the introduction of legislation designed to tackle sectarianism. However, as the Herald reveals today, the Catholic hierarchy now has serious misgivings about the legislation. Bishop Philip Tartaglia of Paisley, considered the most likely next Scottish cardinal, has written to First Minister Alex Salmond, objecting both to the consultation on gay marriage and the legislation to tackle sectarianism, which he regards as a distraction from the real issue. The Church of Scotland has similar reservations. The Herald shares these misgivings.

Sound legislation must be evidence-based. Yet, as the bishop points out, the Scottish Government has failed to publish the figures about sectarian hate crime accumulated over the past eight years, adding to the suspicion that this would reveal most of it is directed against Catholics.

Certainly action is required on internet hate crime but, in the absence of empirical evidence, would the ends of justice be better served by simply enforcing current anti-sectarian legislation more rigorously? Or by marginally widening the definition of breach of the peace to make it easier to target rabble rousers at football grounds?

Badly framed legislation would merely create a legal minefield that will be exploited by football fans who find themselves in the dock for chants or songs that would not be considered offensive elsewhere. There is a thin line between mockery and hate. Also prosecutors will have to show both that the behaviour would be offensive to a reasonable observer and could incite public disorder.

Good law hase to be effective and workable. If it does not lead to successful prosecutions, it will add confusion rather than clarity. There are signs already that this legislation is likely to be provocative, as fans seek to test its limits. Even worse, fans who do behave unreasonably will be likely to portray themselves as martyrs, denied free speech.

Bishop Tartaglia is a significant figure. The insinuation that senior figures in the church hierarchy hold the key to the Catholic vote is exaggerated. Nevertheless, this letter marks a watershed in links between the SNP and the Catholic church.

Warm relations over the SNP’s support for denominational schools and the visit of Pope Benedict XVI, have been negated by disagreements over same sex marriage and now over sectarianism legislation. Meanwhile football supporters run the risk of being pilloried for actions which the Scottish Government appears incapable of defining with any precision.

Nobody denies that sectarianism shames Scotland but poorly conceived and badly drafted legislation risks making a bad situation worse.

As Bishop Tartaglia argues, there is a risk that this legislation will be a distraction from the real menace of sectarianism in Scotland, much of which happens far from the football field.