"Staying in the EU will make the UK more vulnerable to Paris-style terrorist attacks," said Iain Duncan Smith, a senior British Cabinet Minister, to the BBC on 21 February 2016: http://www.bbc.co.uk/news/uk-politics-eu-referendum-35624409. This is a common refrain of the "Leave" campaign, those advocating "Brexit", the UK's exit from the EU in the referendum due to be held on 23 June 2016.
Opposite of the Truth
This threat is exactly the opposite of the truth. Unlike France, the UK has never been part of the Schengen Area and in 1999 was given a formal opt-out from the Schengen Agreement, confirming that the UK was to remain permanently outside Schengen.
Schengen
What the Schengen Agreement did was to abolish all internal border controls within the Schengen Area. So, anyone admitted into one Schengen state could travel freely around the whole Schengen Area without showing any ID. Someone lawfully admitted to, say, Italy which is a member of Schengen, could therefore move freely to any or all of the other 26 Schengen countries without showing ID, including France, Spain, Portugal, Belgium, the Netherlands, Germany, Denmark, and even non-EU states like Switzerland, Norway and, amazingly, Iceland - but not the UK or Ireland, the only two EU member-states with an opt-out from Schengen.
Influx of Migrants
What about migrants and refugees without permission to enter the EU? The influx of over a million migrants from outside the EU placed great pressure on Schengen. Schengen states such as Austria, Germany, France, Denmark, Norway and Sweden reimposed temporary border controls, which is permitted under Schengen in "exceptional circumstances". A more permanent amendment to the Schengen rules is now in the pipeline.
The huge influx into mainland Europe of undocumented migrants and refugees - undoubtedly including a number of terrorists -- can be blamed to at least a certain extent on Schengen.
Britain Cannot Blame the EU
But Britain cannot point the finger at Schengen -- or the EU -- for the terrorists who have undoubtedly slipped in here too. Not being part of Schengen, Britain can impose as many restrictions on admission as the United States or Australia. The fact that it has not done so is the result of two things: the incompetence of the British Government and the political correctness of the UK's own domestic courts - not the European Court of Human Rights.
Britain's Lax Border Controls
Here are two recent examples of Britain's lax border controls:
•The man suspected of masterminding the Paris terror attack on 13 November 2015 that killed 130 people had a picture taken by himself of Birmingham's Bullring on his smartphone: http://www.dailymail.co.uk/news/article-3367355/Bullring-bomb-plot-New-image-Paris-jihadi-s-phone-points-plan-terror-cell-target-Birmingham-shopping-centre.html
•It was reported on 19 July 2015 that someone extradited to the US for terrorist offences slipped back into Britain unnoticed after being released from prison in the US: http://www.thesundaytimes.co.uk/sto/news/uk_news/National/Terrorism/article1582977.ece
The Expansion of Human Rights Law
The European Court of Human Rights in Strasbourg has been blamed by the Conservative Party among others for "mission creep", including giving special protection to asylum seekers and illegal immigrants. In The Problem with Human Rights Law published by the thinktank Civitas in 2015 I showed that the fault lay not with the Strasbourg Court but with the UK's own domestic courts.
The Solution
The threat of terrorism is real, but leaving the EU is not the answer. For one thing, the European Arrest Warrant is an extremely useful tool against terrorism, which would be lost if the UK ceased to be a member of the EU. But above all, as the UK is not part of Schengen, there is nothing to stop the UK from imposing tough border controls. The fact that it has so far failed to do so is not the fault of Europe but of the UK Government itself and of the UK's domestic courts.