For a number of years, consecutive Secretaries of State for the Home Department have increasingly used their powers to deprive individuals of their British citizenship. The use of those powers was recently brought to the public's attention through the widespread publicity of the case of Shamima Begum and the political debate arising out of section 10 of the Nationality and Borders Act 2022, which provides the power to deprive without notice. With the continued growth of decisions to deprive individuals of their British citizenship, the acquisition of British citizenship is no longer the conclusive end to people's immigration journey that it once was. The need to successfully challenge decisions is therefore becoming increasingly commonplace for practitioners. This book examines the evolving area of deprivation of British citizenship, exploring the ways and process by which an individual could lose their British citizenship, as well as the consequences for them, and potentially their family. It also covers the available options and approaches to challenging decisions in light of a number of recent and important judgements. Sean Ell is an experienced barrister specialising in immigration, asylum and nationality law. Prior to practising at the Bar of England and Wales, he was accredited by the Law Society as an immigration and asylum specialist from 2005 and as a supervisor from 2006. He took on a supervisory role at a national charity providing immigration advice, before moving on to work as the immigration supervisor at a Law Centre and then at a regional firm of solicitors. Sean is ranked as a Leading Junior in immigration law in the Legal 500 (Tier 2 - 2023 edition). He was appointed by the Medical Practitioners Tribunal as a Tribunal member in 2011, as a Tribunal Chair in 2015 and as a Legally Qualified Chair in 2019. Chapter 1 - Deprivation of Citizenship Chapter 2 - British Nationality Law Overview Chapter 3 - Deprivation Law and Guidance Chapter 4 - Section 40(2) - 'Conducive to the Public Good' Chapter 5 - Section 40(3) - Fraud, False Representation & Concealment Chapter 6 - Procedure Chapter 7 - Right of Appeal Chapter 8 - SIAC Chapter 9 - First-Tier Tribunal Chapter 10 - Begum, National Security and Appeals Against s.40(2) Decisions Chapter 11 - First-Tier Tribunal (IAC) / Section 40(3) Appeals Post Begum Chapter 12 - Condition Precedent / Discretion Chapter 13 - ECHR Chapter 14 - Consequences Chapter 15 - Nullity Chapter 16 - Loss of Other Types of British Nationality, Right of Abode & Passports