Article 9(2)(a)
Article 9(2)(a) is the UK GDPR (and EU GDPR) condition that permits processing of special-category data on the basis of the data subject’s explicit consent. Article 9(1) prohibits processing of special-category data by default; Article 9(2) lists the conditions under which the prohibition is lifted, and (2)(a) — explicit consent — is the most common one in voluntary-use products.
Article 9(2)(a) does not replace Article 6 (the general lawful-basis requirement); both must be satisfied. For Syndik8’s pilot medical, Article 9(2)(a) is paired with Article 6(1)(a) (consent) to give the lawful basis for storing health data.
In the app: this is the legal grounding behind the consent screen that gates the first medical upload. See Why medicals need explicit consent for the longer reasoning.