Abstract
No earlier EU directive on procurement has emphasised sustainability as much as the current Directive 2014/24 on public procurement (the Directive).1 It clearly states that public procurement is one of the key "market-based instruments to be used to achieve smart, sustainable and inclusive growth."2 Indeed, the Directive may have clarified some matters that have been subject to debate for many years3 - and thereby also the general scope for green public procurement (GPP) in EU public procurement law.4 Nevertheless, the question of how GPP can be conducted still remains unanswered. In fact, the scope for GPP under EU public procurement law may have shifted on a more fundamental level after the introduction of the Directive. Not only has it established what is here referred to as the principle of sustainability,5 but it has also reinforced the idea of open competition by granting it the status of a principle.6 Indeed, while the EU legislator identifies public procurement as a key instrument in furthering sustainability, it also appears to require that sustainability is balanced against the need to ensure "the most efficient use of public funds."7 The question is therefore how these two new, potentially contradictory, principles may be reconciled. Regrettably, little guidance is provided in the Directive as to the more precise meaning and function of the two.