Indeed, it should be reminded that reg.9(4) PCR2015 (and
art 9(3) dir 2014/24) introduces an (unnecessary) cross-referral to the
rules applicable to defence and security procurement for those cases in
which the specific "international" procurement concerns goods, works or
services covered by the special rules. Hence, once more, it will be interesting to try to identify to what extent the rules under reg.17 differ from those under reg.9 PCR2015.
In that light, it is worth reminding that reg.9 PCR2015 established three basic rules: 1) it
creates space for compliance with international law obligations; 2) it creates a specific criterion that money rules,
so that procurement funded by international organisations or
international funders is subjected to their procurement processes; and 3) it allows for negotiated solutions to mix-funded projects, where the
international organisations/funders only provide part of the funds.
Surprisingly (or maybe not), reg.17 PCR2015 establishes the same three basic rules, so that: 1) the rules of Part 2 do not apply to procurement carried out under an international law framework, ie in compliance with the an international agreement or arrangement (including those for the stationing of troops and concerning the undertakings of a member State or a third country) [reg.17(1) PCR2015]; 2) it replicates a specific criterion that money rules,
so that procurement involving defence or security aspects that is funded by international organisations or
international funders is subjected to their procurement processes [reg.17(2) PCR2015]; and 3) it allows for negotiated solutions to mix-funded projects, where the
international organisations/funders only provide part of the funds [reg.17(3) PCR2015].
The only difference between regs.9 and 17 PCR2015 (and arts 9 and 17 dir 2014/24) is in the specific international law instruments that give rise to the exception under the first rule (ie recognition of international law obligations). While reg.9(1)(a) refers to "a legal instrument creating international law obligations, such as an international agreement, concluded in conformity with the Treaties,", reg.17(1)(a) and (b) refer to "an international agreement or arrangement, concluded in conformity with the Treaties" and simply to "an international agreement or arrangement", respectively.
The reader will forgive my limited knowledge of international public law (see Pedro's diverging approach and the enlightening comment that our colleague Dr Paolo Vargiu posted below), but those provisions create no difference whatsoever in my view. The definition in Art 2(1)(a) of the Vienna Convention on the Law of Treaties refers to "Treaties" as "international agreement(s) concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation" (emphasis added). If one resorts to the sources of international law as described in Art 38 of the Statute of the International Court of Justice, there is only one definition/description of internal law that derives from explicit agreements between States, and it refers to them as "international conventions, whether general or particular, establishing rules expressly recognized by the contesting states" [art 38(1)(a)]. It is the general consensus, as far as I can grasp it, that "Treaties can be referred to by a number of different names: international conventions, international agreements, covenants, final acts, charters, protocols, pacts, accords, and constitutions for international organizations. Usually these different names have no legal significance in international law." [Treaties and International Agreements introductory guide, Berkeley Law, accessed 10/03/2015].
Consequently, in my view, reg.17 PCR2015 (and art 17 dir 2014/24) is completely redundant of the rules in reg.9 PCR2015 (and art 9 dir 2014/24) and should have been omitted in the interest of simplification. It would have sufficed, if anything was actually necessary, to include a simple definition (or a reference) along the lines of that in Art 2(1)(a) of the Vienna Convention on the Law of the Treaties. In my view, this is probably a symptom of a deeper problem derived from excessive specialization of law drafters and policy-makers, but that is a conversation for some other time.