As the case of DHL-Leipzig Halle demonstrated, the possibility that contractual measures implementing an unlawful aid measure are invalid and unenforceable can give rise to a curious paradox: where the State assumes a contingent liability that has not yet crystallised, unenforceability of the contractual "advantage" may mean that unlawful aid is, like Schrödinger's cat, both present and absent at the same time. This article looks at the two cases since DHL Leipzig-Halle that have cited the judgment, before considering other areas in which contractual unenforceability of State aid measures can impose adverse – and often unfair – consequences on parties that have received no advantage or benefit from the aid measure in question: State guarantees and warranties and indemnities given to buyers of privatised businesses.
Keywords: Unlawful Aid; State Guarantee; Borrower's Liabilities; Warranties and Indemnities; Privatisation; DHL Leipzig-Halle; Aer Lingus.