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Foreign Terrorist Fighters and UK Counter Terrorism Laws

Professor Clive Walker, Leeds University, presents the main aspects of the UK laws and policies covering from the meanings of ‘foreign terrorist fighters’, criminal justice, policing and prosecution to the Prevent policy.



How have UK counter-terrorism laws and policies adapted to the phenomenon of ‘foreign terrorist fighters’? For these purposes, the focus will be upon persons linked to conflict or terrorism in Iraq and Syria associated with the rise and establishment of Islamic State (Daesh). This broad agenda covers: the meanings of ‘foreign terrorist fighters’ and the formulation of policy against them; criminal justice, policing and prosecution aspects of response; and non-criminal justice aspects of response, including travel and citizenship measures and the Prevent policy.


On 29 June 2014, the leader of the Islamic State in Iraq and Greater Syria (ISIS), Abu Bakr alBaghdadi declared from the Great Mosque of al-Nuri in Mosul the establishment of a Caliphate. Three years later, the leader is said to be dead, the Mosque stands in ruins, and the physical Caliphate has largely been vanquished. Yet, the impacts of Islamic State during the last three years have been momentous and will have enduring political and cultural influences and consequences. The most acute suffering has been, and will be, experienced in Iraq and Syria. But reverberations have been felt elsewhere, especially through the phenomenon of ‘foreign terrorist fighters’ (FTFs).

Aside from military action, official reaction to that phenomenon has been unrelenting. The United Nations Security Council Resolution (UNSCR) 2178 of 24 September 2014 demanded action against the ‘threats to international peace and security caused by terrorist acts, including those perpetrated by foreign terrorist fighters’. This demand was backed by UNSCR 2249 of 20 November 2015, paragraph 5 of which calls for ‘all necessary measures’ against Islamic State. The shape of the state response is to be considered in this article, with an analysis and assessment of how UK counter-terrorism laws and policies have adapted to the phenomenon of FTFs.1 The UK (or, more precisely, England and Wales) is selected as a jurisdiction in the forefront of terrorism legislation(2) but may also be worthy of close scrutiny since it has a high regard for evidence-based policy(3) and for human rights standards.(4)

This inquiry must first define its terms. There is no UK legal definition of ‘foreign terrorist fighter’, though the term ‘foreign fighter’ appears in official documents,(5) with Islamic State depicted as ‘currently the predominant terrorist threat to the UK and our interests overseas’.(6) The chief international definition is in recital 8 of UNSCR 2178 of 15 August 2015, which cites ‘individuals who travel to a State other than their States of residence or nationality for the purpose of the perpetration, planning, or preparation of, or participation in, terrorist acts or the providing or receiving of terrorist training, including in connection with armed conflict’.(7) There is no further definition of ‘terrorist’, though the collection of international criminal law and counter-financing treaties provide some elucidation. As for secondary commentaries, one influential scholar has argued that foreign fighting involves ‘any military activity (training or fighting), using any tactic (terrorist or guerrilla tactics), against any enemy (Western or nonWestern)—so long as it occurs outside the West.’(8)

There remain several elements of controversy )within these attempted definitions, especially if the version not qualified by the term, ‘terrorist’, is adopted. In that case, a wide range of activities can be encompassed, especially involvement in foreign state forces and in private military companies, whether as a committed volunteer or as a paid or conscripted recruit. This extension sparks debate about why involvement in past conflicts, such as the Spanish Civil War,(9) has been condoned (or even revered)(10) and also why contemporary UK citizen service in the military of foreign states, such as the French Foreign Legion (acting in Operation Barkhane) or the Israel Defence Force (in Palestine), does not spark official disquiet.(11) Of course, there are crucial distinctions from Islamic State in that French or Israeli state forces are committed to abide by international law and have not been condemned as organisations by the United Nations. Furthermore, the joining of official state forces will not per se amount in UK law to ‘terrorism’. As for involvement in activities of private military companies, so long as they operate within national and international law, especially those following the International Code of Conduct for Private Security Service Providers 2012,(12) such activities are likely to be treated as legitimate, illustrated by the use of heavily armed guards on ships in the Gulf of Aden.(13) Next, the definitions do not exclude fighters who claim citizenship of the conflict state or kinship ties to its residents or even a broader common bond through religion. Aside from being an inappropriate qualification in an internecine conflict, as far as UK counter-terrorism law is concerned, such links are rejected as amounting to legal justification, save perhaps for a claim to the immediate defence of blood relatives.(14) Finally, whether the fighter is paid or not seems less crucial. Many groups designated as terrorist have made payments to ‘volunteers’, including Islamic State, but payment is not a prime motivation in the case of foreign fighters in Syria and Iraq.(15)

Foreign fighting is nothing new,(16) even for the proponents of jihad some of whom have previously participated in conflicts in Bosnia, Chechnya, Somalia, and Afghanistan.(17) Indeed, Al Qa’ida’s involvement in the resistance to Russia in Afghanistan, incorporating mainly Saudi and Egyptian contingents, was ‘pivotal’ to its development.(18) However, the ongoing conflicts in Iraq and Syria, associated with the establishment of the Islamic State of Iraq and the Levant (ISIS) (2013–14) and then Islamic State (Daesh) (2014 onwards), have instigated greater apprehensions about FTFs than in most previous conflicts. Amongst the causes are: proximity and accessibility of the battlefield; the deployment of social media to spread inviting messages; and the scale and diversity of opportunities for volunteers associated with the assumption of statehood rather than some clandestine terrorist vanguard.(19) As a result, the current threat level for international terrorism in the UK was raised to SEVERE on 29 August 2014 because of the activities of Islamic State; according to Prime Minister David Cameron, ‘what we’re facing in Iraq now with ISIL is a greater and deeper threat to our security than we have known before’.(20) The threat has both qualitative and quantitative aspects.

The qualitative threat from Islamic State coalesces around several elements. One is the outward challenge to international law, policy, and peace, a problem marked out by the aforementioned UNSCRs. The second is the domestic threat, whereby FTFs seek to inspire and recruit others at home. Thwarted FTFs who are intercepted before reaching their destination may then seek more proximate targets. Most serious of all, returning FTFs can apply back home military techniques, logistical networks and status to inspire others.(21) Early doubts about the seriousness of this domestic threat(22) have been starkly dispelled by mass deaths from attacks in Belgium, France, Tunisia, and Turkey during 2015 and 2016.(23)

In quantitative terms, around 22,000 FTFs have been involved in Syria and Iraq, mostly from the Middle East and North Africa.(24) Up to 5,000 Europeans have been recruited.(25) As for the UK, the official estimate as at 30 June 2016 is that around 850 UK-linked individuals of national security concern have travelled to engage with the Syrian conflict; just under half have returned, and approximately 15% are deceased.(26)

The epithet, ‘terrorist’, can become somewhat misleading if applied to all. Many travellers (including most females) intend, or are assigned, to engage in acts of solidarity of a humanitarian or support nature and not in combat. As for trends, two features emerge. One is that rates of recruitment and travel have been downwards from its peak in 2014.(27) Possibly, the allure of Islamic State has reduced, and security measures against travellers have improved. The second is that the reduced rate of travel may not immediately correspond to a lesser threat because of the dispersal of FTFs or through strategic displacement.(28)

Four comments may be distilled from the foregoing discussion. The first relates to terminology.(29) Terms such as ‘travellers (outgoers)’ and ‘returnees (incomers)’ would be more comprehensive and less charged than ‘foreign fighters’ or ‘foreign terrorist fighters’. However, those latter terms have established currency in international discourse, though their inexactitude should contend against any attempt to build legal rules around them. As between those two terms, the narrower term, ‘foreign terrorist fighter’, should be preferred to ‘foreign fighter’, since it is based on the UN precedent and avoids the thorny issues around foreign state or private company enlistment. The term, ‘foreign terrorist fighter’, should further be clarified by specifying the different risk categories of those within the chosen terminology so as to provide a better picture.

Second, the FTF phenomenon is insufficiently reflected in policy statements. It is to a limited degree mentioned in the UK Government’s Countering International Terrorism (CONTEST) strategy annual reviews.(30) However, measures against FTFs have not been stated in one chapter of CONTEST or any other specific policy paper, unlike the position for other countries,31 the European Union(32) and United Nations.(33) CONTEST is currently under substantial revision for the first time since 2011;(34) a specific segment which draws together the FTF policy responses would be opportune.(35)

The UNSCR 2178 of 24 September 2014 demands the institution of state policy about FTFs, while also reaffirming observance of obligations under international human rights law, international refugee law, and international humanitarian law.(36) States must prevent suspected FTFs from entering or transiting their territories and must enact legislation to prosecute FTFs (articles 1–10).(37) This UN demand for action has been reinforced by the Council of Europe’s Additional Protocol to the Council of Europe Convention on the Prevention of Terrorism 2015, which requires the criminalisation of participating in an association, receiving training, or travelling abroad for the purpose of terrorism.(38) The European Union has signed the Convention and Protocol,(39) and has also developed a Directive on combating terrorism (40) and a slew of other policies,(41) including the introduction of a European Passenger Name Record system,(42) measures on radicalisation,(43) and the strengthening of Europol through the setting up of the European Counter Terrorism Centre and the EU Internet Referral Unit.(44)

Having set the scene, this article next analyses the UK responses to FTFs. The prime concentration in the next section will be on criminal justice policing and prosecution, much of which resides within special terrorism legislation. That will be followed by scrutiny of the myriad of non-criminal justice responses, including travel and citizenship measures and the Prevent policy,(45) some of which are non-legal interventions.

Keep reading and access the full article here.

Suggested Citation:

Walker, Clive, Foreign Terrorist Fighters and UK Counter Terrorism Laws (November 26, 2018). (2018) 2 Asian Yearbook of Human Rights and Humanitarian Law 177-204. Available at SSRN: This PaperOpen PDF in Browser


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