I'd sit with Rosa Parks for the right to take a bus. I'd march with Martin Luther King for the right to vote. I'd probably even take up arms with Nelson Mandela for the right to be a citizen in my own land. But there's no way I'd go to court with Trevor Phillips for the right to join a party that would want to expel me and my family from the country. Of all the equality issues to be taking a stand on, surely this must be the most ridiculous ever conceived.

On Tuesday the Equality and Human Rights Commission, which Phillips chairs, wrote to the British National party over "possible breaches of anti-discrimination law". The commission says it "thinks" the BNP's constitution and membership criteria "may discriminate on the grounds of race and colour". It thinks? In case it hadn't noticed, the BNP's own constitution says the party's membership is "strictly defined" within "the legal ambit of a defined 'racial group' this being 'Indigenous Caucasian' and defined 'ethnic groups' emanating from that Race".

This is consistent with its stated mission, to represent the "collective National, Environmental, Political, Racial, Folkish, Social, Cultural, Religious and Economic interests of the indigenous Anglo-Saxon, Celtic and Norse folk communities of Britain and those we regard as closely related and ethnically assimilated". Is the BNP ­racist? Well, is the Pope Catholic?

I'm all for taking action to counter these bigots – restricting the BNP's ability to spread its message of hate and banning its members from public service roles such as teachers and police. But what would the commission's course achieve? If the BNP wins the case, it gains masses of publicity, is able to claim it has seen off the PC brigade – and Nick Griffin's smirk and his odious propaganda will be all over the media. If the commission wins, the BNP gains masses of publicity and can bemoan an oppressive PC brigade – and Nick Griffin's smirk and his odious propaganda will be all over the media.

Even if the BNP agrees to amend its membership rules before the case goes to court, it will be reported that the party has done the "decent" thing – giving more weight to Griffin's ludicrous, though worryingly effective claim that his is a respectable and legitimate party.

And what will the commission have gained from all of this? The right for black or Asian people to join a party which spreads fear and hatred about them; which claims they can never be British; and which wants, ultimately, to repatriate them. Who does Phillips think will be signing up? Turkeys, you really can vote for Christmas.

These are worrying times. The BNP is filling a vacuum which other parties, especially Labour, created by running after middle England's votes while ignoring the working classes.

Among large swaths of the population it is no longer shameful to speak up for the BNP, and the party has been helped by the useful idiots fighting their corner in arguments over free speech. Would these people – most of whom have no understanding of what it's like to be the victim of race discrimination – have backed Hitler? Do they not see that blaming minorities for social and economic problems appeals to a gut instinct that is not easily overcome by learned arguments? Above all, publicity, and the sense that others think like you, is what drives support for these groups.

Rightly or wrongly, the BNP is a legal party – and its membership rules are true to its core philosophy. The last thing we want is to needlessly martyr it or give it a respectability it doesn't deserve. The commission must call off its action before granting Griffin and his cronies any more photo-opportunities.