There is a tendency in BrExit circles to conflate EU Freedom of Movement with the broader problem of migration, including refugees, asylum seekers and economic migrants from outside the EU. There is a claim, much made by Farage, that the UK has no control over its borders and we must leave the EU to regain that control. They take every opportunity such as the Paris and Brussels terrorist attacks to assert that outside the EU we would not be exposed to such attacks.
Firstly, let me make it clear: if we leave the EU, not a single person in war torn places like Syria will decide to stay where they are instead, rather than leave for Germany, Sweden or even the UK. Not a single person in camps outside Calais and other French ports will decide to return home or even seek refuge in France or another EU country. If a migrant makes it to the Schengen area intent on reaching the UK they will still be able to.
Secondly, leaving the EU makes no legal difference to the rights of migrants to enter the UK. The UK can prevent them now and will be able to after BrExit. The reason migrants are camped in appalling circumstances outside Calais is because the UK is refusing to permit them to enter the UK, not because they can’t afford to buy a Eurostar ticket to cross over the the UK. Leaving the EU will ensure that EU citizens and residents are subject to the same immigration regime (unless we agree to a Norway like situation in which Freedom of Movement is maintained) but makes no difference to non-EU migrants.
It is often claimed that a refugee who gains asylum in (say) Germany, can then move to the UK and immediately claim benefits. This isn’t true. So, leaving the EU doesn’t suddenly stop people in these situations moving to the UK. Even if it were true, it’s not a particularly great strategy for (say) ISIS to infiltrate the UK with terrorists as it can take upto 10 years to get German citizenship. The evidence of the 7/7 and 21/7 bombings, the Lee Rigby murder, Richard Reid (the “shoe bomber”) and other (mainly thwarted) plots is that there are plenty of UK citizens willing to undertake terrorist acts and BrExit won’t protect us from them nor will EU membership make them more likely. Indeed, the speedy return of Hussein Osman (the 21/7 bomber that fled to Rome) under the EAW is evidence that EU membership helps improve security.
The impact the UK would have on migration is that it will be that much harder for Europe as a whole to solve the problem of migration from Syria and other war torn regions. The cooperation of France post-Brexit to manage our joint border can no longer be assumed (indeed probably won’t happen).
The idea that BrExit magically solves all migration problems, at least insofar as Britain is concerned, is deluded nonsense. British voters may have many other reasons for leaving the EU, but if they expect that solving migration, or insulating the UK from migrants, is one of them, or even the most important, then they will be very disappointed.