To break Brexit talks deadlock the EU must agree ‘sufficient progress’ has been made – what does that mean?

The term “sufficient progress” is embedded within the European Council’s negotiating guidelines for Article 50 – the part of the EU treaty which governs how a state leaves the bloc. It is born out of the EU’s phased approach to the Brexit negotiations, which was later confirmed by both the EU and the UK in June 2017. Agreeing whether there has been been sufficient progress means solving these three key problems: the status of UK citizens in the EU and EU citizens in the UK, the border between the Republic of Ireland and Northern Ireland, and the settlement of the UK’s financial obligations. What the agreed solution ought to look like, however, is more elusive.