I'm at a demonstration outside the Israeli embassy. People are waving Israeli flags around me, chanting in support of Israel's right to defend its citizens. A Californian rabbi is speaking about the Jewish state. As a proud Zionist, I should be in my comfort zone. But I've rarely felt more uncomfortable in my life.

Because side by side with the Stars of David are hundreds of angry, jeering members of the English Defence League, there to "oppose Islamic fascism". They are the sort of thugs I'd avoid if I met them on the underground late at night; absolutely not the sort I want to stand with at a rally for Israel.

The legacy of that day in October 2010 is to remind us that our enemy's enemy - I use "enemy" in a very broad sense - rarely has a place as our friend. Indeed, that's a very dangerous starting point for supporters of Israel.

Last week an apparently "controversial" pro-Israel New York lawyer was blocked from speaking at Leeds University - not because anti-Israel students objected, but because the JSoc decided that her previous association with Dutch politician Geert Wilders made her persona non grata. Having not heard Brooke Goldstein speak - although she did so elsewhere - I can't comment on whether her presence would indeed have jeopardised the welfare of Jewish students.

But, whether wrongly in this instance, our JSocs are right to be vigilant. When it comes to Israel, British campuses are battlegrounds, full of fired up students with tendencies to jump on trendy bandwagons and a compulsion to prove their counter-cultural credentials. Those that claim the modern undergraduate is apathetic are not looking hard enough; Israel, at least, gets them shouting.

Jewish students are right to be vigilant

For the JSocs, on the frontline, the debate invariably comes down to free speech versus incitement. Is discourse enough of a reason to offer the extremist a platform; is it right to allow those with a vested interest to preach to malleable minds? The answer has varied from place to place. Despite uproar, Dominique Strauss Kahn addressed Cambridge students; more controversially, the Jenny Tonges, Azzam Tamimis and Gilad Atzmons have been able to air their views. Pro-Israel
students have at times reacted angrily and called for action when invitations have been extended to such speakers, with varying degrees of success.

It's their prerogative to oppose having these elements on their campuses, of course, and up to them to counter the charge of stifling free speech, which they must be wary of.

But above all, they must guard against accusations of double standards. If it's ever going to be "one rule for them, one for everyone else" it should be so only in that the rule for those who advocate for Israel and for the welfare of Jews is to be better, more careful, to always act above reprimand or reproach.

It's easy to say with hindsight that someone is controversial, or isn't. It's easy to stand from afar and scoff that this radical is not too radical, that they are just the right side of extreme. But if we claim that, we must accept it will be volleyed back with a passion.

Perhaps everyone should be given a platform, no matter whether they have advocated for Hamas or spewed venom at the Jews. Hiding hate does no good; maybe we should encourage extremists to talk themselves out of credibility. It's not something that can be easily resolved. But decisions must be taken with a recognition that actions have consequences. Our arguments become weaker if we leave ourselves vulnerable. And, ultimately, the responsibility for such decisions lies with those who have to negotiate the fallout.