The Federal Constitutional Court declines to accept for decision a constitutional complaint against extradition to South Korea — not because of the detention conditions, but because, within the time limit for reasons, the complainant failed to engage with the second, subsequent OLG order. Where a further order under Section 33 IRG follows the admissibility decision and entails a fresh examination on the merits, the two form a single procedural unit ("verfassungsprozessuale Einheit").
What the case was about
The case concerned the extradition of a Turkish national for prosecution in the Republic of Korea. After the constitutional complaint — combined with an application for interim relief — was received in time on 21 January 2026, the Chamber, by order of 9 February 2026, provisionally prohibited the surrender: the complaint was "neither inadmissible in its entirety from the outset nor manifestly unfounded", and the challenged order of the Higher Regional Court (Oberlandesgericht, OLG) Frankfurt am Main of 19 December 2025 "pointed, as regards the size of the cell space assured by the Republic of Korea, to a violation of the specialized courts' duties of investigation arising from Art. 19(4) sentence 1 GG".
The OLG then obtained, via the Federal Foreign Office, supplementary information and assurances from the Korean authorities (note verbale of 5 March 2026) and, by order of 30 March 2026, rejected an application for a renewed decision on admissibility; an overall assessment of the supplementary information showed that the complainant could expect "reasonable detention conditions". By letter of 5 May 2026 the complainant extended his constitutional complaint to cover this second order.
The decision
The constitutional complaint is not accepted for decision (Section 93a(2) BVerfGG) because it is inadmissible; the interim order of 9 February 2026 thereby becomes moot. The Land of Hesse must reimburse the complainant for the necessary expenses incurred in the interim-relief proceedings; the value in dispute for those proceedings is set at EUR 7,500.
The decisive reasons
The reasoning of the constitutional complaint does not meet the requirements of Section 23(1) sentence 2 BVerfGG and Section 92 BVerfGG. Where the complaint is directed against a court decision, it requires "as a rule a detailed argumentative engagement with the challenged decision and its specific reasoning".
The submissions did not satisfy this standard: although the complainant had addressed the order of 19 December 2025, within the time limit for stating reasons (Section 93(1) sentence 1 BVerfGG) he had not engaged with the considerations in the order of 30 March 2026. The decisive sentence reads:
"Where, after a decision has been issued on the admissibility of the extradition, a further order is issued in the proceedings under Section 33 IRG, the complainant must also engage with the subsequent decision, provided that it involves a fresh examination on the merits of the conditions of admissibility. For in that case the two decisions become a single procedural unit ("verfassungsprozessuale Einheit")."
In its order of 30 March 2026 the OLG had re-examined the reasonableness of the detention conditions — after obtaining supplementary information and assurances. The complainant did not engage with that examination; his letter of 5 May 2026 "addressed only parts of the reasoning […] that do not concern the assessment of the detention conditions decisive for the grant of the interim order". He had thus failed to set out, with sufficient particularity, that he was still being violated, after 30 March 2026, in his right to effective legal protection under Art. 19(4) sentence 1 GG.
Significance for practice
The decision is an object lesson in the procedural architecture of multi-stage extradition proceedings. Successfully raising, at the interim stage, a violation of the specialized courts' duty of investigation as to detention conditions does not yet win the case: if the OLG responds — as here — with a fresh examination on the merits under Section 33 IRG, that second order merges with the first into a single procedural unit. The burden of substantiation then extends to both decisions, and it is time-bound. If the subsequent decision is not challenged, or only incompletely, the constitutional complaint fails on admissibility — regardless of whether the detention conditions were soundly investigated on the merits.
It is also notable that the Land of Hesse must bear the costs of the — successful — interim-relief proceedings, despite the failure of the main proceedings.
Extradition and constitutional-complaint proceedings are a dynamic process: every new decision of the specialized courts must be brought into the complaint within the time limit and worked through argumentatively. The "single procedural unit" is not an intuitive matter of course but a trap that must be known in order to be avoided — which is precisely where early, specialized representation pays off.
Citation: BVerfG, order of 21 May 2026 — 2 BvR 143/26.
Source: Full text at bundesverfassungsgericht.de (decisions 2026).
Context: Fourth and final stage of the "Korea complex": OLG Frankfurt (2 OAus 88/25) of 19 Dec 2025 → BVerfG, interim order of 9 Feb 2026 → OLG Frankfurt of 30 Mar 2026 → this decision. See also OLG Frankfurt, stage 3 (30 Mar 2026) and BVerfG, interim order (9 Feb 2026).