This thesis focusses on litigation for migrants' rights in the UK, and in particular litigation conducted by lawyers and activists motivated by the cause of promoting and protecting migrants' rights. The thesis conceptualises this form of migrants' rights activism as ‘cause litigation'. The thesis asks the question, what happens when immigration and migrants' rights questions are litigated for political purposes in the UK? In answering this question the thesis shows that cause litigation has in some circumstances been able to develop some highly significant forms of rights-protecting systemic change. However, the thesis also shows that cause litigation is vulnerable to adverse Executive reactions. Executive conduct in the area of immigration and migrants' rights is governed by an overarching imperative to exercise and be seen to be exercising control. Cause litigation presents direct challenges to this imperative. In response to these challenges the Executive has engaged in both evasion and an increasingly aggressive backlash against changes secured through cause litigation and the activity of cause litigation itself. This backlash has succeeded in undermining many of cause litigation's achievements and has ultimately diminished the role of cause litigation and the rule of law in regulating immigration control in the UK. This is not to argue that the advancements obtained through cause litigation are irrelevant; those that survive, albeit in a reduced form, are non-negligible in the otherwise highly adverse context of the UK's immigration politics. Cause litigation is, therefore, one of the few avenues open for migrants' rights to be protected and advanced, even if it is in a compromised and vulnerable form. It is argued, though, that an activism technique that was a response to the political disadvantage migrants' rights campaigners face, by securing practical change without mainstream political support, has ultimately not been able to escape from the UK's adverse immigration politics.

This thesis studies Turkish migration policies as an outcome of the interactions between the European Union, international organisations (UNHCR, IOM) and domestic migration governance. Counterbalancing a tendency in the literature to focus on external influences and specifically the EU's power over candidate countries, Turkish migration policy is seen to result from interrelationships between external and domestic actors that vary according to context of policy type, time and relative balance of power between the actors. Changes in international relations, Turkey's relationship with the EU, and internal to migration governance, can relativize the power asymmetry between EU and Turkey, leading to opportunities for domestic authorities to exert influence. The study has a comparative design across four cases of migration policy decision-making and by actor-type. This allows investigation of interrelations and an actor's efforts to exert influence relative to the others. A prominent policy is examined for each of the main four fields of Turkish migration policy: legislative reform (Law on Foreigners and International Protection), irregular migration (EU-Turkey readmission agreement), regular migration (adoption of the EU's visa lists) and asylum (removal of geographical limitation clause from the 1951 Refugee Convention). Document analysis is supplemented by original data from twenty-one semi-structured interviews, conducted with experts from Turkish Ministries, international organisations and the EU Commission. The main finding is that the degree of external influence over Turkish migration policy is contextually shaped, by time, the substance of a specific policy field, and most notably by the degree to which a policy field is politicised. EU influence is strongest when a policy field is politicised and driven by ‘conditionality'. International organisations are less influential actors but present in shaping more technocratic and less politicised policies through ‘social policy learning'. Turkish authorities exert clear agency and use international negotiations to gain leverage to advance domestic migration interests.