ZM (R on the application of) v LONDON BOROUGH OF CROYDON

Evidence from dental development may assist an age assessment, but it must be treated with considerable caution. Statistical evidence cannot by itself establish a plausible individual fact merely because it produces a probability above 50 per cent. The reference population must be sufficiently comparable to the person assessed.

Complete dental maturity at Demirjian stage H does not reliably establish whether a person is over 18. Mandibular maturity markers and dental wear require adequate scientific validation and appropriate population data. A dental tomograph should generally be ordered when sought in an age dispute: its small x-ray risk will ordinarily be outweighed by the benefit of obtaining relevant evidence, subject to any special individual risk.

The applicants challenged age assessments by the London Borough of Croydon. Each claimed to be an Afghan child entitled to services under the Children Act 1989, but Croydon had assessed him as over 18.

Croydon applied for permission to rely on dental-development evidence from Professor Graham Roberts. It also sought orders requiring each applicant to undergo a dental panoramic x-ray, with strike-out or a stay if he refused. The applications raised the reliability and proper use of dental evidence, the limits of statistical reasoning in individual age assessments, and whether the radiation risk justified refusal.

The Tribunal heard extensive expert material and considered the Court of Appeal decision in London Borough of Croydon v Y [2016] EWCA Civ 398. It gave general guidance and determined whether the proposed tomographs should be ordered.

1. The respondent's applications were granted. The applicants were directed to undergo dental x-rays. The parties could rely on expert interpretation subsequently obtained. Following the hearing, Croydon accepted ZM's claimed age and his judicial-review claim was withdrawn by consent; SK's claim continued.

2. An age-assessment court must determine, on the balance of probabilities and on all available evidence, whether the person was a child at the relevant time. That inquiry is not confined to choosing between the claimed age and the local authority's assessment. Statistical material requires particular caution. A database must be sufficiently comparable with the person assessed, and a numerical probability above 50 per cent does not itself prove an individual fact.

3. Dental evidence can be relevant but must not be overvalued. Demirjian stages below stage H may assist, especially where several teeth remain immature and the person is in the lower teens. By contrast, fully mature dentition at stage H is only a sign of maturity and is not a reliable indicator of whether a person is above or below 18. The three identified mandibular maturity markers lacked sufficient scientific acceptance to be treated as reliable late-teen age indicators. Dental wear requires data from a population with comparable diet and chewing habits.

4. London Borough of Croydon v Y [2016] EWCA Civ 398 did not create a universal bar on refusing a dental examination. The question remains whether refusal is reasonable in the individual case. Ordinarily, the small radiation risk from a dental tomograph is outweighed by the substantial benefit of obtaining evidence relevant to correct age assessment. A special individual risk may require separate consideration. The earlier the tomograph is taken, the more likely it is to disclose useful immature-tooth evidence.

5. Expert opinions must disclose a sound, current and properly qualified evidential basis. Reports resembling the sample report from Professor Roberts should be approached with great caution, particularly where they present precise age conclusions from unreliable, incomplete, non-comparable or mutually dependent data.

• Upper Tribunal (Immigration and Asylum Chamber): determined Croydon's interlocutory applications in the judicial-review proceedings and ordered dental tomographs.
• High Court: permission for ZM's judicial-review claim was granted by Picken J, after which the claim was transferred to the Upper Tribunal.
• High Court: permission for SK's judicial-review claim was granted by Sir Stephen Silber, after which the claim was transferred to the Upper Tribunal.