Jim Murphy said last week that the stain of religious sectarianism would only be gone from Scotland when it is "seen by future generations to be just as unacceptable as racism and homophobia".

Murphy was promising to get rid of the Offensive Behaviour At Football And Threatening Communications (Scotland) Act. It is safe to say a majority of football fans, particularly in Glasgow, would applaud him for that. They say, with evidence, that the police have gone over the score in enforcing the law; that existing legislation served well enough; that sectarianism is more complex than any trouble surrounding football.

Chris Graham, of the Rangers FC group the Union Of Fans, told The Herald that the implementation of the act had been "virtually impossible". He also advanced an argument that is hard to refute: there is a problem in deciding what we mean by offensive. Have you committed a criminal act just because your ­opinions are not to someone's taste?

On the one hand, that is patently the essence of laws against racism and homophobia. Equally, you can be accused (take it from me) of ­intolerance towards people of faith simply by being satirical about their beliefs and where beliefs can lead. Such folk can be dreadfully offended. Should they also be entitled to call the cops?

Joe O'Rourke, of Fans Against Criminalisation and the Celtic Supporters' Association, argued that the act was "a knee-jerk reaction". Previous restrictions "already covered anybody who misbehaved at football matches".

Meanwhile, one sheriff has described the "horribly drafted" 2012 legislation as "mince". Murphy prefers the word "gimmick". Last week, only the SNP held out against repeal in a Holyrood debate called by Labour.

So: poorly drafted, unnecessary legislation that misses the point, is unpopular, impossible to implement, and brings the threat of prosecution to the cloudy realm of personal belief and opinion. It amounts almost to a textbook definition of bad law. Hence Murphy's promise.

But hold on, as anyone who has ever witnessed or suffered bigotry and sectarianism in Scotland might interject. This issue didn't become one of our wee national trademarks for nothing.

Contrary to anything Murphy might suggest, the act wasn't conjured up with no excuse. The Scottish reputation, particularly in the west, didn't spring from nowhere. The fact that middle-class Catholic professionals are no longer contained by the old glass ceiling is not proof of a problem solved.

It is no accident that racism and homophobia are increasingly, as the MP observes, unacceptable. Times and society have changed; education has drained many old poisons. But some pretty sturdy laws - like the law being upheld by the Equality Commission in Northern Ireland - have been needed. Murphy's commitment to dump the football act if he is lucky enough to become First Minister overlooks the ­obvious: unacceptable is not the same as non-existent.

The East Renfrewshire MP also overlooked a couple of other things in his intervention. One involved the opinion polls showing that Scottish Labour won't be legislating for anyone any time soon. Just as important is the fact that, even should his luck turn to a remarkable degree, Murphy will not be in a position to scrap the act before 2016. In the meantime, an assessment of the legislation's impact will have been produced by the Scottish Government.

What if the law is working? After all, that was the claim made last week by Roseanna Cunningham, the Community Safety and Legal Affairs Minister. Meanwhile, a Government spokesman asserted that "religiously aggravated offending" fell by 17% last year. Are Labour opposed to that sort of result? Shouldn't Murphy at least wait until the assessment group reports next year?

Better still - for perhaps I missed it in his soundbites - shouldn't the MP tell us how he would handle the issue? He is a Celtic fan and a devout Catholic. He knows the history of this ugly reality as well as anyone. Last week, he denounced the act as an attempt to chase headlines. He said - correctly - that "sectarianism and intolerance goes far beyond 90 minutes on a Saturday or 140 characters in a tweet". Then he proposed "education". And that was it.

Meaning what? Anything that hasn't been tried for decades? Anything that would cope with the phenomenon of online bigotry for which the act was, in part, designed?

Murphy was less interested in offering a better response to sectarianism than in attacking the SNP. No-one expected otherwise, but it wasn't exactly a help in the Scotland he imagines he will one day govern.

The legislation's tendency to criminalise football fans as a type is an old story where the sport is concerned. Previous efforts to deal with hooliganism fell into the same trap. Attempts by Uefa, European football's governing body, to have clubs punished for the actions of a minority face the same difficulty.

Hardest of all, always, is the effort to evolve rules to cope with sincerely-held yet utterly horrific opinions when individuals claim a human right.

But that does not mean that the law can never help.