Ian Katz
Newsnight Editor

It is a pre-requisite of every police procedural drama that the main protagonists rubbish any rival law enforcement agency at every opportunity. Tonight’s Newsnight special on whether the EU makes us safer wasn’t quite Starsky and Hutch but duly produced its own bit of inter-agency drama.

One of the central arguments of the Remain camp is that Brexit would jeapordise the access of British police and security forces to valuable European intelligence databases. But when former Met counter terror chief Richard Walton and Europol chief Rob Wainwright skirmished on this point, Walton did not pull any punches. The European databases were of “marginal value” and, anyway, Europol dramatically overestimated its role. “It’s not even a law enforcement agency. It has never made an arrest in its history.”

Wainright waited till the last moments of the debate to seek revenge. In a post Brexit world where Britain was seeking to tighten its own border controls, what databases would the UK rely on to decide who to keep out? Europol of course. 

Evan Davis
Newsnight Presenter

My thoughts on the security debate.

I think the Leave side probably felt frustrated that most of the time, they didn't get much chance to make the positive security case for leaving. Instead of getting across the idea that we would be safer outside, they were left arguing the much less attractive proposition that we simply wouldn't be unsafer.

The two arguments they did deploy to make the case that the EU actually harms safety focused on the threat to Nato from the possible creation of a European army; and better control over who comes into our country. Both involved some disputed factual interpretation of EU practices and intentions, and that blunted the impact.

Here's that film from Mark Urban setting out the scene - with analysis and views from top miltary figures and experts.

Busy and packed programme. Here are a few key quotes:

This ComRes poll from back in November suggests that the public think that being members of the EU strengthens Britain's national security.

Read into it whatever you like; we're all still sceptical of the polls. 

Secunder Kermani
Newsnight correspondent

Image source, Getty Images

As the recent, deadly attacks in both Paris and Brussels showed – terrorist networks are transnational. But do we need to be part of a transnational group like the EU to combat them? Or does that make us more vulnerable?

To carry out the attacks, a cell of Belgians, French, Swedes and Iraqis travelled back from Syria – some disguised as refugees – before moving across the continent. 

Others, providing logistical support, were also able to travel around mainland Europe laying the groundwork for the attacks.

Some Brexit supporters have claimed this shows the dangers of the Schengen Zone - and the lack of internal borders within the EU. Weak border entry points in Greece they say are allowing terrorists to reach our doorstep. 

But whether Britain remains or leaves the EU – that won’t change. Either way potential attackers could still get to ports leading to the UK.

Supporters of the remain campaign say counter terrorism efforts are improved as part of the EU – where we can share intelligence. In reality though security services across the EU aren’t always keen to share information and resources.

Everyone agrees so-called Islamic State poses a threat to the whole of Europe - but "leave" and "remain" have very different ideas on how Britain should respond to that. 

Here are a few of your tweets. Keep them coming at #newsnight

But Colonel Richard Kemp didn't agree that the two issues are entirely separate...

There is no EU-wide intelligence-sharing arrangement. There are direct agreements between certain member states. These are not dependent on membership of the EU.

The UK's biggest intelligence relationships lie outside the EU. It shares intelligence with the US and with three other English-speaking countries: Canada, Australia and New Zealand, forming the "five eyes" alliance.

While there is no EU-wide intelligence agency, there is an EU-wide enforcement agency - Europol. 

More from Reality Check here

Image source, Getty Images

Most of the examples that people talk about here, like the 12-year-long case of AbuQatada, have been rulings emanating from the European Court of Human Rights (ECHR) or rulings of British courts under the Human Rights Act (HRA).

Crucially, the ECHR is not an EU body. Repeat; the ECHR is not an EU body.

So leaving the EU wouldn't be enough to get around the convention. The UK would also have to withdraw from the ECHR and abolish the Human Rights Act. 

The court which is part of the EU is the European Court of Justice (ECJ) which determines when EU citizens can be deported. The threshold to deport EU citizens is already quite high, (holding a criminal conviction isn't enough, the person must pose a threat to the interests of society). The threshold also goes up after five and 10 years of residence in the UK. 

Even more confused? Read more over at Reality Check

Image source, Getty Images

EU freedom of movement allows citizens of all the other 27 EU countries to travel freely to the UK, to visit, study or work. There is a UK border, and everyone, including citizens of EU-member states, has to produce a passport to cross it. In practice, holders of EU passports are not routinely subjected to detailed checks.

Admission to the UK can be blocked "on grounds of public policy, public security or public health", according to EU rules. Under no circumstances can it be on economic grounds...

Reality Check verdict: The UK refuses a tiny fraction of EU nationals who want to come here. It has to have very good grounds to do so. In the case of criminality, for example, a conviction even for a serious crime in not good enough - the individual must pose a current risk.

Read the full article here

"We currently face an unprecedented global threat from terrorism that is not confined to one region or continent. Our response needs to be global to defeat it.

"From my own experience as Head of the Counter-Terrorism Command at New Scotland Yard, I believe that Britain’s national security depends on many different factors but membership of the EU is not one of them. Our intelligence agencies and counter-terrorism police are envied across the world and routinely share intelligence across international boundaries and Brexit would not affect this. Membership of the EU does not convey any benefits that we couldn’t access if we were outside it. 

"It is a mistake to believe that Europol and Frontex are contributing to our national security. They are not law enforcement agencies and undertake no counter terrorism operations. In reality, both are largely irrelevant to day-to-day operations within the counter-terrorism sphere. The Schengen Information System is useful but has limitations and you don’t need to be part of the EU to use it. The European Arrest Warrant is very rarely used in terrorism operations and normal extradition procedures are adequate to handle such cases."

Richard Walton was head of Counter Terrorism Command at New Scotland Yard 2011-2015

"In today's complex and unstable world international terrorist networks, cyber crooks, and mafia groups pose a grave threat to Britain's security. They are operating within our midst or on our doorstep. Those who carried out the attacks in Paris and Brussels were home-grown European jihadists. London could be next. 

"To counter that threat cooperation with the US will always be important but, given the nature and proximity of the problem, British authorities also place a high premium on working closely with European partners. 

"Some of that engagement occurs within the intelligence community. But, increasingly in the field of counter terrorism and almost exclusively in the areas of combating drug trafficking, child sexual abuse networks and modern slavery for example, unique EU cooperation systems play a vital role in keeping Britain safe. These include the Schengen Information System, the largest security database in Europe with 64 million alerts, the European Arrest Warrant, and a platform for intelligence sharing and operational coordination at Europol connecting over 600 law enforcement agencies around Europe and beyond. 

"These days Britain can't guarantee its security without continued access to these, something which would be placed in doubt if it left the EU. Important security considerations rest on the outcome of the vote on 23 June."

Rob Wainwright is director of Europol