In Onuzi (good character requirement: Sleiman considered) Albania [2024] UKUT 144 (IAC) the Upper Tribunal dunks on my old case of Sleiman:

1. Each case is fact sensitive. In the absence of a statutory definition of ‘good character’, the starting point is for the Secretary of State to decide, subject to general principles of administrative law, whether a person is of good character for the purpose of granting citizenship under section 6(1) and Schedule 1 of the British Nationality Act 1981 (‘BNA 1981’).
2. Any negative behaviour that might cast doubt on whether a person is of good character is likely to be directly material to the assessment of the statutory requirement, whether it played a role in the application for naturalisation itself or took place before the application. 
3. In the majority of cases where negative behaviour that might cast doubt on whether a person is of good character has been dishonestly concealed from the Secretary of State, the fact that the negative behaviour might not have been directly relevant to an earlier grant of leave is unlikely to make any material difference to the assessment under section 40(3) BNA 1981. It is for the Secretary of State to decide, subject to general principles of administrative law, whether the negative behaviour might have made a material difference to the assessment of good character under section 6(1) BNA 1981 had the information been known at the time.
4. The omission of a fact that might have cast doubt on whether a person is of good character when they applied for naturalisation is likely to be material to the question of whether a person ‘obtained’ citizenship by the dishonest concealment of a material fact for the purpose of section 40(3) BNA 1981.
5. The concept of a chain of causation being broken is only likely to be relevant in cases where there was full disclosure and the Secretary of State exercised discretion to grant leave to remain or naturalisation while in full possession of the facts.
6. The decision in Sleiman was based on limited argument and should be read in the full context of the statutory scheme and other relevant case law.

This certainly narrows down the available arguments in these citizenship deprivation cases. The Onuzi determination is a strange one, though. There’s no sign of recognition that the exercise the tribunal is supposed to be undertaking here is a review of the original Home Office decision on public law grounds only. This is unsurprising for the original First-tier determination, which predates the case of Chimi. It’s more surprising of the Upper Tribunal’s decision, which reads a lot like a forbidden merits review.