In May 2016 an organisation JC readers may not be familiar with  the International Holocaust Remembrance Alliance  agreed a working definition of antisemitism.

Importantly, although Israel isn’t mentioned in the definition, the IHRA notes that some kinds of criticism of Israel can constitute antisemitic behaviour or speech. For example, holding Jewish people accountable for government policy, or events in Israel, may be antisemitic. But the definition does not make criticism of Israel itself antisemitic.

The definition has a long history: it is based on a formula drafted by the European Monitoring Centre on Racism and Xenophobia (EUMC) in 2005. Non-governmental organisations in the UK have called for the adoption of the EUMC definition for years.

This week, Theresa May announced that the UK would formally adopt the IHRA definition. Some have greeted the move as a terrible step; they say free speech is being attacked. Others say it is a welcome decision which should have been made years ago.

The definition will be used by the police, councils, universities and public bodies. But will it have any tangible effect in practice?

It is not a piece of legislation. There is no Act which has gone through debate in Parliament which has now made antisemitism unlawful. The police won’t be able to make arrests, and the CPS will not be able to prosecute individuals on the basis that they are “being antisemitic”. The antisemitic aspect of any activity will have to be shoehorned into existing ways to prosecute individuals, such as harassment or assault.

And there may be little impact on the courts, at least initially. As is often the case with definitions drawn up by international bodies, it is vague.

However, it will be a very useful tool; it can help public bodies decide whether an incident is antisemitic or not.

If law enforcement bodies have a clear definition that they can understand, the antisemitic elements of offences will be easier to prosecute.

This includes attacks via social media as well as physical attacks. Although there are a significant number of laws which address hate speech or deed, a definition of antisemitism (taking into account the new ways anti-Jewish sentiment is expressed) is needed to assist bodies to clarify when certain words or allegations are in fact antisemitic.

If the relevant bodies learn to refer to it frequently, and are able to use it effectively, then the definition may inform them whether offensive conduct or words need to be addressed; and it will provide a framework in which — in simple terms — it will be easier to bring to justice those who attack Jewish people.

Dina Shiloh is a partner at Gallant Maxwell Solicitors