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Jennifer Thelen

“Jennifer provides excellent advice on complex matters.  She is approachable and very practical in her advice which is always appreciated by clients.” Chambers and Partners, 2023. 

Jennifer has a broad legal background, having practised both corporate and regulatory law before being called to the Bar. That breadth is reflected in her practice. Jennifer is a member of the Attorney General’s A Panel of Junior Counsel to the Crown. Jennifer has an active public law practice. She frequently represents central and local government and is experienced in national security, education, immigration prisons, tax, local government law and regulatory law.   She has a growing information rights practice and frequently advises on and appears in data protection and freedom of information claims. She continues to advise public authorities on discrimination and employment claims.

Areas of expertise

Administrative and Public

Jennifer has a broad public law practice.  She has appeared in a large number of judicial reviews regarding healthcare, pensions, prisons, immigration, tax and education, both as sole and junior counsel.  She is instructed, on behalf of the Secretary of State, in a number of matters before the Special Immigration Appeals Commission, including high-profile challenges to decisions to deprive individuals of their citizenship. She has, given her background a keen interest in commercial judicial review. 

Cases of note:

  • U3 v Secretary of State for the Home Department - The appellant was deprived of her citizenship and denied entry clearance on the basis that she had travelled to Syria and aligned with ISIL. The Appellant challenged these decisions, on the basis that she was not ora risk to national security. This was one of the first cases to be heard in the Special Immigration Appeals Commission (SIAC), which applied the approach to a national security assessment following the Supreme Court’s decision in R (Begum) v SIAC.  Currently, this case is on appeal to the Court of Appeal. Jennifer served as junior counsel to the Secretary of State.
  • Wilson v Commissioner of the Police of the Metropolis - Jennifer served as Counsel to the Tribunal (junior counsel). The Claimant successfully challenged the use of undercover police officers to spy on protest groups in the 2000s. The Investigatory Powers Tribunal found that the practices used violated the Claimant’s rights under Articles 3, 8, 10, 11 and 14 of the European Convention on Human Rights. 
  • R (Khurana) v North London CCG & NHS England - Jennifer represented the CCG (as junior counsel) in this challenge to the sale of a number of GP practices to a large US corporation. The case was the first to examine the factors a CCG is required to take into account when considering a change of control clause.
  • R (Gaztony) v Secretary of State for the Home Department - Jennifer represented the SSHD in the High Court in this unlawful detention case considering the responsibility for detention of a person who is awaiting treatment for a mental health condition, and where there are issues identifying an appropriate treatment facility. 
  • (R) BMA v Secretary of State for Health and Social Care - Jennifer represented the BMA in the High Court in a judicial review of regulations which brought back the power to suspend the receipt of a public service pension to charge rather than conviction of a serious offence.  The Claimant successfully established its claim brought under A1P1, read with Article 14, as well as Article 6 and the public sector equality duty. 
  • Shamima Begum v Secretary of State for the Home Department - Jennifer represents the Secretary of State in this appeal of a decision to deprive the Appellant of her citizenship following her travel to Syria as a 15-year old (as junior counsel).
  • L3 v Secretary of State for the Home Department - Jennifer represented the Secretary of State in this challenge to the decision to exclude a Libyan citizen (as junior counsel).  The Applicant received permission to appeal the decision of the Special Immigration Commission to the Court of Appeal on two grounds relating to his family and private life. The Court of Appeal’s decision (awaited) will consider the approach to the best interests of the child, and Zambrano, in the context of a national security challenge. 

Information and Media

Jennifer has a strong information rights and data protection practice. Jennifer has been instructed in leading FOIA cases, including on the interpretation of the national security exemptions to FOIA. She regularly appears before the First-tier and Upper Tribunal in FOIA cases.  She has been instructed twice in challenges regarding algorithms and artificial intelligence, as well as a challenge to an Enforcement Notice issued by the Information Commissioner. She regularly advises public authorities on data protection and information rights, including regulators and local government. 

Cases of note:

  • HM Attorney General v BBC - Jennifer represented the Attorney General (as junior counsel) in this claim brought to restrain publication, by the BBC, of allegations that an individual was an agent, or covert human intelligence source, for the Security Service, and that X was a dangerous extremist and misogynist who abused two female partners.  The case considered both the appropriate approach to human rights balancing where national security concerns are engaged, as well as open justice issues.
  • Foreign Commonwealth and Development Office v Information Commissioner and Williams - Jennifer represented the Foreign Commonwealth and Development Office, initially as junior counsel and then as sole counsel, in this challenge which concerned the appropriate approach to sections 23 and 24 of FOIA.  The Upper Tribunal held that it was appropriate to refer to sections 23 and 24 of FOIA.
  • Ofgem v Information Commissioner - Jennifer represented the Office of the Gas and Electricity Markets in this challenge to Ofgem’s decision to treat a requestor who sought emails from senior Ofgem officials over a number of days as a “fishing expedition” and therefore vexatious.  The First-tier Tribunal rejected this approach, finding that the public interest in disclosure outweighed the burden on Ofgem. 
  • Dr Emma Briant v Ministry of Defence - Jennifer represented the Ministry of Defence in this challenge to an refusal to either confirm or deny that a report regarding research and communication campaigns was held, within the meaning of FOIA, on the basis of defence and national security. 
  • Ofgem v Information Commissioner and Scottish Power - Jennifer is representing the Office of the Gas and Electricity Markets in this challenge to a decision to withhold information regarding an ongoing enforcement process, in reliance on internal communications and course of justice exemptions to the Environmental Information Regulations 2004. 
  • R (Hendy) v Information Commissioner and the Animal and Plant Health Agency - Jennifer represented the Animal and Plant Health Agency in this challenge in the Upper Tribunal to a First-tier Tribunal decision which found that the Appellant was a vexatious litigant.


Jennifer has a long-standing education practice.  She regularly represents local authorities, central government, higher and further education bodies, schools and individuals in education-linked matters.  She has been instructed in a number of high court challenges across a wide range of education disputes, including teacher regulation, the treatment of political issues, higher education disciplinary proceedings, education in prisons and education and health care plans (“EHCPs”).  She has extensive experience in the First-tier and Upper Tribunals in challenges to EHCPs, disability discrimination claims and school registration, and has represented education institutions in disability discrimination claims in the County Court and High Court.  She was instructed in a 7-week trial in the Chancery Division on behalf of a local authority in a fraudulent conspiracy claim involving a maintained schools.  She advises on a range of education matters, including funding of special educational needs, the public sector equality duty, school admissions and school exclusions.

Cases of note: 

  • Brent LBC v Davis and others - Jennifer was instructed by the local authority as a junior to Hefin Rees QC, in a seven-week trial in the Chancery Division in a fraudulent conspiracy claim made by the London Borough of Brent against senior management, and governors, of Copland School (see also Local Government Law), as well in the related professional negligence claim (against the auditors).
  • R (Kharanja) v University of West Scotland - Jennifer represented the University of West Scotland in this preliminary issues challenge, on service and jurisdiction. The substantive claim concerned a challenge to the University’s decision to withdraw the Claimant from its Defendant’s Doctor of Business Administration programme.  The claim was rejected at an early stage on grounds of late service and jurisdiction.
  • R (Rowe) v Secretary of State for Education - Jennifer represented the Secretary of State for Education in this challenge to the use of the Secretary of State’s powers under sections 496 and 497 of the Education Act 1996. 
  • R (Ellis) v Secretary of State for Education and Secretary of State for Justice - Jennifer is representing the Secretary of State for Education and Secretary of State for Justice in this challenge to the student finance regulations as they apply to prisoners. 


  • “…Jennifer is very pragmatic.” Chambers and Partners (2023)
  • “…Jennifer has extensive experience in acting in public law cases for both central government departments and local authorities. She has a huge capacity for hard work and her turnaround rate is quick and superb.” The Legal 500 (2022)
  • “…She has an encyclopaedic knowledge of education law and is exceptionally skilled cross-examiner."  The Legal 500 (2022)