Introduction to the concept of free movement
The Treaty of Rome  envisaged from the onset a common market and economic policy between MSs characterised by free movement  within the internal borders of the European Economic Community (EEC). Currently, the EU laws that govern free movement and border controls are laid out in the Treaty on the Functioning of the European Union (TFEU) and the Protocols of the Lisbon Treaty  . The right to free movement of workers is governed by Articles 45 to 48 TFEU  . Article 45 guarantees workers the right to free movement within the territories of the MSs of the Union, without any form of discrimination based on nationality (Article 45 (2)TFEU) but subject to limitations justified on grounds of public policy, public security or public health (Article 45 (3) TFEU). Article 45 continues at section three that this right includes moving freely within the territory of MSs for the purpose pertaining to the work in question (Article 45 (3) (b) TFEU) and residing therein even after stopping work subject to conditions in regulations to be drawn up by the European Commission (Commission) (Article 45 (3) (c) and (d) TFEU).
Chapter two of Title IV, TFEU enumerates the law regulating the right to establishment under free movement laws  . Article 54 states that ‘Companies or firms formed in accordance with the law of a MS and having their registered office, central administration or principal place of business within the Union shall... be treated in the same way as natural persons who are nationals of MSs’  .
Another area of free movement involves ‘Services’ – which is covered by Chapter three of Title IV, TFEU  . Article 57 states that ‘Services shall be considered to be “services" within the meaning of the Treaties where they are normally provided for remuneration, in so far as they are not governed by the provisions relating to freedom of movement for goods, capital and persons’.
The free movement of persons within the EU is further stated in Title V on the Area of Freedom, Security and Justice (AFSJ) TFEU  , Article 67 (2) where it says that the Union ‘...shall ensure the absence of internal border controls for persons and shall frame a common policy on asylum, immigration and external border control, based on solidarity between MSs, which is fair towards third country nationals (TCNs).’ At sub-section 3 it continues that ‘The Union shall endeavour to ensure a high level of security through measures to prevent and combat crime, racism and xenophobia, and though measures for coordination and cooperation between police and judicial authorities and other competent authorities, as well as through the recognition of judgments in criminal matters and, if necessary, through the approximation of criminal laws.’ At Article 72 it goes further to state that ‘This Title shall not affect the exercise of the responsibilities incumbent upon MSs with regard to the maintenance of law and order and the safeguarding of internal security.’
Policies on border checks, asylum and immigration are contained in Articles 77-80 TFEU. The law states that ‘The Union shall develop a policy with a view to: (a) ensuring the absence of any controls on persons, whatever their nationality, when crossing internal borders; (b) carrying out checks on persons...’  Article 79 TFEU at section 1 covers EU competencies on common immigration laws and continues at sub-section 2 that the EU shall adopt measures in the following areas: (a) conditions of entry and residence and standards on the issue by MSs of long-term visas and residence permits, including those for the purpose of family reunification; (b) the definition of the rights of TCNs residing legally in a MS, including the conditions governing freedom of movement and residence in other MSs; (5) This Article shall not affect the right of MSs to determine volumes of admission of TCNs coming from third countries to their territories...’
Article 26 TFEU states that ‘The Union shall adopt measures with the aim of establishing or ensuring the functioning of the internal market...’; (2) The internal market shall comprise and area without internal frontiers in which the free movement of goods, persons, services and capital is ensured in accordance with provisions of the Treaties., 
The EU laws governing free movement will not be complete without mentioning the rights of citizens of the EU to move freely within the territories of the MSs save for, reasons bothering on public policy, public security or public health. Article 20 states that ‘Citizenship of the Union is hereby established. Every person holding the nationality of a Member State shall be a citizen of the Union. Citizenship of the Union shall be additional to and not replace national citizenship. (2) Citizens of the Union shall enjoy the rights and be subject to the duties provided for in the Treaties. They shall have, inter alia: (a) the right to move and reside freely within the territory of the Member States’.  The right to free movement for citizens is further explained thus ‘Every citizen of the Union shall have the right to move and reside freely within the territory of the Member States, subject to the limitations and conditions laid down in the Treaties and by the measures adopted to give them effect.’ 
The laws enumerated so far should be legally binding on the UK, being Treaty laws, however, the UK has derogated from some of them, that is, those that concern TCNs. The laws that concern citizens cannot be derogated from by the UK. Among the laws that do not apply to the UK include those spelt out by Protocols 19  , 20  and 21  of the Treaty of Lisbon.
Protocol 19, Article 4 states that ‘Ireland and the United Kingdom of Great Britain and Northern Ireland may at any time request to take part in some or all of the provisions of this acquis.’ This law governs the mode of ‘opt-in’ or ‘opt-out’ by the UK, in measures concerning the Schengen Acquis  – which is an area very much like a single state for international travel with border controls for those travelling in and out of the area, but with no internal border controls.
Protocol 20 provides that nothing in EU law – especially Articles 26 and 77 TFEU, affects the right of the UK to exercise control on persons entering from other parts of the EU or elsewhere. Effectively, this means that the UK can check anyone entering its territory for the purpose of verifying if the person in question possesses the right of uninhibited entry (EU citizens and their dependants and others accorded the right by agreements with the EU which binds the UK), and impose border control measures on TCNs even if they possess a Schengen visa.
Protocol 21, in respect of the AFSJ provides that ‘the UK will not participate in Title V of Part Three TFEU and that no measures adopted under the Title or any Court judgment interpreting it shall bind them.’  This means that the UK is not party to any feature measures in the AFSJ until further notice.
Therefore, the effect of these derogations is that the UK is bound to apply EU laws and measures that concern areas of free movement not covered by the derogations in the Protocols.
Early in the formulation of free movement rights ‘EC legislature  acknowledged that family members of migrant workers, irrespective of their nationality, also benefitted from the free movement provisions.’  The areas affected are free movement of citizens and their dependants now covered by The Citizens Right Directive 2004/38/EC  (CRD) amending Regulation (EEC) No 1612/68 and repealing Directives 64/221/EEC, 68/360/EEC, 72/194/EEC, 73/148/EEC, 75/34/EEC, 75/35/EEC, 90/364/EEC, 90/365/EEC and 93/96/EEC. This Directive applies to the UK and its provisions have been transposed into domestic law in the Immigration (European Economic Area) Regulations 2006  (2006 Regulation).
The CRD ‘now provides the framework for almost all legal issues concerning the free movement of persons – right to movement and short-term residence.’  Article 4 to 6 of the 2004 Directive provides that ‘citizens may move throughout the territory of the Union and live in any state for up to three months, without formalities other than the possession of a valid identity card or passport.’  Article 9, CRD requires all MSs to issue residence card to TCNs for stay longer than three months. Therefore, the Treaty provides a directly effective right to free movement for the categories of people listed therein  . The European Court of Justice (ECJ) had in Akrich  developed the notion of ‘prior lawful residence’ (PLR) for family members of migrants resident in a MS to take advantage of free movement rights. The subsequent decisions of the ECJ in the cases – Jia  and Eind  caused uncertainty in the application of the law.
The decision in Metock  , now reaffirmed in Sahin  has disposed of the use of PLR but ‘leaves open questions about the applicability of Metock to extended and atypical family members and to the various return and tenuously transborder scenarios already recognized as falling within the scope of the Treaty.’  The approach of the ECJ shows that it ‘has moved beyond the discrimination model and, returned to the language of Article 3 (1) (c) EEC (now repealed), it has focused instead on removing discriminatory and non-discriminatory “obstacles" or “restrictions" to free movement.’ 
The free movement of people raises security and welfare issues and that is why the UK has opted out of almost all measures on the Schengen Acquis. This is also replicated in the AFSJ where the central issue is ‘the balance between protection of human rights and civil liberties on the one hand and the States’ interest in public order, security, or immigration control on the other.’ 
Under free movement provisions, ‘the right of EC (now EU) companies to send their TCN employees to other MS, as part of the corporate provision of services,  may have implications for visas and border controls.’  The ECJ held in Vander Elst  that such workers have a right of entry and residence in the MSs where the services are provided but only to the extent necessary to provide the services and without any right to join the employment market of the host state.
In a report to the Parliament  on JHA matters, the government stated that ‘the UK participates in some parts of the acquis as recorded in Council Decision 2000/365/EC (OJ L 131, of 1 June 2000, p. 43-47), that is, the police and judicial cooperation elements of Schengen (the UK does not participate in the frontier control elements).’ The report expressly stated that there was no intention of joining Schengen measures that could weaken UK border controls – this confirms the position of the UK with regard to free movement. The EU has, in realisation of the need to reach a fair balance between these competing rights and the UK’s insistence that internal and external security are core matters of sovereignty, allowed the derogations mentioned above. Moreover, ‘terrorist attacks in Madrid (2004) and London (2005), but also enlargement towards Central and Eastern Europe have fuelled public awareness and fear... illegal immigration is perceived by large majorities of European citizens as a threat to their security...’ 
The European Council  asks the Commission to adjust its upcoming communication on the application of the Directive to ensure that it facilitates the Council’s security-oriented agenda.
These issues of security concerns by the UK have necessitated its non-participation in a number of Directives granting free movement rights to certain categories of TCNs. These Directives include, but not limited to, Directive 2003/86 on the right to family reunification; 2003/109 on long-term residence; 2004/114 on student’s right of admission; 2005/71 on admission of researchers; and 2009/50 on highly qualified migrants (EU Blue Card Directive). The above mentioned Directives would have afforded TCNs who wish to enter the UK ‘free movement rights irrespective of their relationship with an EU citizen.’  The UK does not participate in FRONTEX and RABIT (Regulation 863/2007) and the Border Code Regulation (562/2006).
One of the objectives of the Stockholm Programme  is to approximate the rights of legally resident TCNs to those of EU citizens and to encourage the migration of labour between the EU and other States as a way of increasing the Union’s competitiveness. The EU has weighed these competing rights and granted the MSs some national discretion with regard to who to admit into their territory. Therefore, ‘the Stockholm Programme equally re-affirms the distinction between Community citizens and TCNs in respect of free movement rights.’  More recently, ‘the European Council adopted ‘Europe 2020’, the new EU economic strategy for the 21st century (replacing the reference to the preliminary agreement of March).’ 
Hans Lindahl rightly pointed out that ‘Freedom, as the free movement of persons, depend on the boundary that closes off the internal market from an external market. The “persons" involved are, to be sure, citizens and legally resident third country nationals. Security, too, is bounded; in the Commission’s words, “the full benefits of any area of freedom will never be enjoyed unless they are exercised in an area where people can feel safe and secure".’ 
In conclusion, the balancing of free movement rights with the rights of the citizens to a secure UK is really dependent on the way the community understands these two rights. Alun Gibbs aptly argues that ‘...this reason emerges from the reflection about the quotidian acts or decisions that determine how a political community comes to understand its constitutional commitments and symbolic meanings. Hence, balance must be seen as making sense of our overall experience of living in a political community that has expressed a commitment to different ‘goods’, through the particular decisions or acts of that political community.’ 
The position of the UK is helped by the fact that it is an Island with natural frontier barriers that militate against illegal migration and assist in ensuring the security of the Country is not easily compromised by aliens and others taking advantage of free movement rights. The bombing of 2005 was perpetrated by citizens of the UK, bolstering the argument that the concerns of security goes beyond the admission of TCNs into the UK. The UK has been able to keep out of the Schengen area because of this geographical feature. Therefore, the effort of the UK government towards guaranteeing security to its citizens is not in any way hindered by these TCNs. The EU has been able to reach a fair balance, in my opinion, in securing security for the citizens of the EU as well as affording citizens and TCNs free movement rights. The EU achieves the security of their citizens by policing the external borders to stem the influx of undesirable TCNs and thereby managing permitted migration. The MSs reserve the right to exclude or expel TCNs and this is shows that security takes precedence over the rights of certain individuals.
It has been reasoned that ‘Mobility rights constitute one of the central elements in the definition of a Community approach to the rights of TCNs, but they seem not to have been granted the attention they deserve.’