As a feminist cause célèbre, the case of Lubna Hussein, is hard to top. She is the Sudanese journalist facing a public flogging and unlimited fine if a Khartoum court finds her guilty of wearing a pair of trousers. Light green ones, to be precise. Hardly an anarchist's uniform, unless you live in Sudan, where wearing trousers constitutes "indecent clothing". If you're a woman.

Sudan's public order police swooped on Hussein, right, and 12 other women similarly clad in a Khartoum café, charging them with violating public decency. Ten of the women accepted their lot – 10 lashes and a fine of about £65. But Hussein, a 30-something widow, who faces 40 lashes if convicted, is so outraged at the affront on her personal freedom that she is fighting her case. The trial was last week adjourned until next month. To do so, she has resigned her job as a United Nations press officer, because that would have given her immunity from prosecution and ruined her chance of "defending the women of Sudan".

Hussein's plight has made headlines around the world, spawned countless blogs and even merited a mention from the French President, Nicolas Sarkozy, he of the anti-burqa brigade. Classic feminist fodder, you might think. And yet, there is one missing element in the indignation at the injustice of Hussein's fate: her Western sisters. Their absence is glaring from a nascent internet campaign to eliminate Article 152 of Sudan's criminal law, which decrees trousers, a routine option for British women, "indecent" or "scandalous".

The brief list of international groups supporting the online petition comes from countries such as Pakistan, Egypt, Malaysia, and even Afghanistan, but not, you can't help notice, from Britain, the United States, or even France. A placard held by one of the 100 or so protesters who gathered outside the Khartoum court may have proclaimed that "Lubna's struggle is every woman's", yet that's not the impression you get from London.

Where are the women protesting outside the Sudanese embassy? Where are the feminists sticking up for the basic human right to put on what you like when you get out of bed? Where are the calls to impose tough sanctions against Sudan for oppressing women, as we did against South Africa for oppressing the majority black population in its apartheid days? Where, in short, is the International Sisterhood?

Apparently it's too busy worrying about whether lads' mags such as Nuts and Loaded are degrading to women (yes) or if pictures of impossibly skinny models dent a woman's self-confidence (need I answer?). Or if women are misrepresented in adland as bloated, constipated, greying airheads overwhelmed by laundry.

And our politicians are hardly helping matters. Where was their condemnation ahead of Hussein's hearing? They were too busy worrying about whether men should be trusted to run things (Harriet Harman) or about magazine pictures being airbrushed (this from the Liberal Democrats' new policy on women's issues). Now that women have largely won the big political fights in this country, Harman's concerns notwithstanding, we sisters, it seems, are too busy picking personal fights over assaults on our personal image or perceived discrimination in the workplace to worry about the big political fights still to be won in countries such as Sudan. That, at any rate, is the view of feminists such as Jean Edelstein, an author and journalist, who believes that the second wave of feminism has gone soft, with concerns about work-life balance and gender-related pay gaps taking precedence over hard issues such as subjugation of women and sexual violence.

Add to that the pervading doctrine of cultural relativism – that an individual's beliefs should be understood in terms of their own culture – and it becomes very difficult to find anyone publicly banging the feminist drum for the likes of Hussein. Especially when you consider that your typical left-leaning feminist would regard it as anathema to meddle in another country's affairs. "Women who do," said Edelstein, "run the risk of being labelled anti-Islam, racist, or naive."

This may explain why it has been left largely to bloggers, often hiding under pseudonyms such as Mary Quite Contrary, to turn Hussein into that cause célèbre.

"This is feminism at the coalface, isn't it?" wrote one last week. "Certainly puts the 'debate' about shaving legs and it being OK to like pink and still be a feminist into stark perspective!" Another asked: "Where are the feminists? Where is the outrage? If this was some conservative Christian sect that beat their women for wearing pants can you imagine the coverage this type of thing would get?" Another, Pamela Geller in the US, called the silence of women's movements "scandalous, shameful, complicit in the horrible suppression of women in Islam".

I'm not suggesting that the case of Muslim women's issues is in any way cut and dried. President Sarkozy may regard the burqa as a "sign of subservience" but it's clear that many choosing to cover up would disagree. Some see it as part of their identity, while others view it from a feminist standpoint: covering up for them is their own rejection of beauty fascism.

But when it comes to getting dressed, surely the right to wear what you like is a basic human right. Ban Ki-moon, Secretary-General of the United Nations, thinks so. And so does Lubna Hussein, who is prepared to endure the ultimate humiliation of a public flogging to give the issue a global airing.

"Tens of thousands of women and girls have been whipped for their clothes these past 20 years. I want these women's voices to be heard," she said. Surely this is long overdue.