As we have noted several times, one of the options that he potentially could go for is an "emergency brake" - the ability to impose temporary restrictions on the number of EU migrants who come to the UK.
We can see why this would be appealing politically - but we fear that if Cameron does announce something like this, without having a clear vision for how it would work exactly in practice, it could turn into another net immigration target. Sounding very good in an election manifesto - but ineffective in practice.
We've made this point a few times but to elaborate, here's why:
An emergency brake would be targeted at flows of new EU migrants not the existing stocks. UK Ministers have previously spoken about the need to manage “destabilising flows” – however, this remains a vague term that could mean many different things. Pinning down what would constitute a destabilising flow could prove incredibly tricky. For example, the graph below shows that current flows are not proportionately higher than previous flows and remain small as a share of the workforce (relevant for their impact on wages). In general, if the bar is too high, the mechanism will never be used. If too low, the brake would become a long-term rather than temporary measure – a de facto limit – and be tremendously hard to negotiate in Europe.
What the UK would effectively be asking for is a ‘time out’ from EU migration – which is largely a result of understandable political pressures. However, this necessarily makes the criteria for pulling the ‘emergency brake’ politically arbitrary – and in turn tougher to negotiate in Europe. There's not a government in Europe, it now seems, that doesn't have a populist challenge. Should Spain be granted dispensation too?
It's also difficult to sell at home. There are precedents in EU law for restricting either free movement of persons or the other EU freedoms. So in that sense, an emergency brake wouldn't be completely out of character for the EU. All of the existing 'brakes', however, are policed by the European Commission and the European Court of Justice – would a domestic audience be happy with such an arrangement? Furthermore, at the very best the brake is likely to be temporary and may only delay flows rather than actually reduce them. It would have to be activated for a very long time in order for it to really reduce net flows in the long-term.
In addition, if ‘cost of living’ is to be cited as a reason for pulling the emergency brake, it means accepting that there is a ‘cost of living crisis’ – a move that would any UK Government would be politically loathed to make in public.
If someone can come up with a criteria for how to capture all the potential variables, then we're open to suggestions. But it would be foolish to announce such a big policy on such loose grounds. As we've argued repeatedly, writing the headline first, and the policy later, rarely works.