The Labour Party has dropped a disciplinary case against a member of Jewish Voice for Labour after she threatened to sue it for discriminating against her because of her anti-Zionism.

Diana Neslen’s lawyers had argued that her view represented a “protected belief” under equality law.

According to the Guardian, in 2017 she had tweeted that “the existence of Israel is a racist endeavour and I am an anti-racist Jew”.

Her wording shows that she was clearly taking a shot at the International Holocaust Remembrance Alliance definition of antisemitism, which includes as one of the possible examples of it: “denying the Jewish people their right to self-determination eg by claiming that the existence of the state of Israel is a racist endeavour”.

The Labour Party did not adopt the full IHRA definition until 2018.

I am no lawyer so I hesitate to say what the merits of her legal claim might have been. But the Equality Act talks of discrimination on grounds of “religious or philosophical belief”. And Ms Neslen’s view seems to be more of a political position than a “philosophical belief”.

A political party must surely have some leeway in deciding that certain positions are incompatible with membership of it and a person should find another party more hospitable to their views. A party, for example, set up to promote Brexit would surely be free to exclude someone who promised to campaign for the UK to rejoin the EU.

But there are ways that anti-Zionism could be seen as a “protected belief”. Take a Satmar Chasid, who regards the idea of re-establishing a Jewish state before the advent of the Messiah as heresy.

Suppose a Satmar Chasid applied for a job to teach maths at a central Orthodox Jewish school - admittedly, an unlikely scenario. If the prospective teacher was turned down because they belonged to an anti-Zionist sect, their religious viewpoint would be irrelevant to the subject they were going to teach and hence they might have a legal claim against the school.

But stretching credulity once more, if the Satmar applied to be a Jewish studies teacher in a religious Zionist school, then the school would have stronger grounds for refusing them.

The outcome of a tribunal case may often be unpredictable and equality law can contain a sting in the tail. The classic example of that is the Supreme Court ruling on JFS 13 years ago.

Until then, it had been normal for Jewish schools to admit children on the basis of whether they were halachically Jewish or not - that is, on their mother’s Jewish status. But the courts decided that simply awarding places according to parental origin breached race relations law. The case in the High Court had actually gone in favour of JFS. It is not the only instance where the development of equality law has affected Jewish schools.

And so while Jewish communal organisations look on equality law as a source of protection for members of the community, the law can spring an unwelcome surprise.