Anti-semitism is often used by the unscrupulous as a convenient allegation to smear opponents, (much as witchcraft was in the Middle Ages and peadophilia has been in more recent times). It is an utterly heinous crime, invoking memories of the holocaust and concentration camps and, rightly, seen as being completely beyond the pale. Consequently, it is an accusation difficult to defend against or recover from. The problem nowadays is that it is frequently (and deliberately) confused with anti-Zionism, (which is somewhat different) or simply being critical of the Israeli government. Personally, I'm critical of some of the Israeli government's policies with regard to the Palestinians and the occupied territories. But that doesn't mean that I hate Jews, Israelis or even the Israeli state itself, which I believe has a right to exist and defend itself. But I sometimes fear that we're getting to a stage where expressing such opinions might become next to impossible for fear of being labelled an anti-semite. But it isn't just with regard to Israel and the Jewish people that there are attempts to restrict the expression of some opinions through allegations of racial or religious hatred. We already have some groups telling us that we shouldn't make blanket condemnations of the activities of ISIS as it implies a belief that all Muslims are terrorists. Utterly nonsensical, but incredibly, such a view has gained currency in some quarters. You'll see a similar situation across a whole range of issues where various interest groups are attempting to narrow the debate to what they have decided is an acceptable range views - all dissenting opinions will be shouted down and those who dare to express them condemned as extremists. Sadly, you can find these self-appointed thought censors on both the left and right.
But we've drifted away from the original issue of alleged anti-semitism in the Labour Party. Is it a problem? I have no doubt that you can find people holding such extreme views in the Labour Party, just as you undoubtedly could in any large organisation, but I'd be very surprised to find that it was widespread. Of course, the left's traditional championing of the cause of the Palestinians has always laid them open to allegations of anti-Zionism and anti-semitism from their opponents. But that isn't a problem confined to the Labour Party: traditionally, the UK political establishment has been perceived as more pro-Arab than pro-Israeli. To return to the original point, I guess that what I want to say is that when allegations of this type start flying around the media, we always need to be careful to check who is making them and what their motivations might be.