Code of Public Contracts, Anac, Guidelines n. 8 of October 10, 2017, in GURI of 23.10.2017, Appeal to negotiated procedures without prior publication of a notice in the case of supplies and services deemed irretrievable, art. 63 or art. 125 for the special areas of Legislative Decree 18.4.2016, n.50

In the cases and in the circumstances referred to in Article 63, contracting authorities may award public contracts in a negotiated procedure without prior publication, providing adequate justification in the first act of the existence of the relevant conditions.
The contracting authorities must ensure a comparative assessment between several offers with the minimum presence of five operators, if any, and adequate rotation. More caution and guarantees are provided.
In the hypothesis of the sole supplier, the so-called “non-negligible” goods and services are available, and both the legislator Ce and the nation have foreseen exceptions to public evidence because of the discounted result and a number of resources and time.
When establishing the conditions for legitimate use of the derogation here, the contracting stations may bear in mind the Community and national case law.
The determination of the inability of the goods, in accordance with settled case-law of the Court of Justice, for all, Case C-337/05 of 8 April 2008, in the judgments of the Court of Justice, must be interpreted restrictively, of its justificatory presuppositions, and of the State Council, Sez III, 08.01.2013 n. 26: ‘the negotiated procedure without publication of a contract notice is of an exceptional nature with respect to the contracting authorities’ obligation to identify their contractor by competitive confrontation, so that the choice of such a procedure requires a particular rigor in the identification of the justificatory prerequisites, to be strictly interpreted and it is the burden of the contracting authority to prove its existence. ”

Curia Sources, Administrative Justice and Anac