The principles of equal treatment and transparency laid down in Article 2 of Directive 2004/18 must be interpreted as not precluding ‘the inclusion in a public works contract of a clause which, in order to establish the temporal scope of a guarantee obligation on the part of the contractor and for matters on which that clause is silent, refers to the provisions of the national civil code’ (Opinion, C-82/24, point 81).

However, these principles are not compatible ‘with an interpretation of that clause which, by extending the guarantee period beyond what was agreed by the parties, could not be foreseen by a reasonably well-informed and normally diligent contractor’ (Opinion, C-82/24, point 81).

Introduction

The submission of a sustainable economic offer that guarantees an adequate profit margin requires the assessment of all costs and risks (not only those related to the project execution) which could lead to additional costs for the contractor.

Among these risks, the legal risk is vitally important when it comes to assessing the scope of ambiguous clauses imposing very burdensome obligations on the contractor.

In that regard the duration of the guarantee period for defects in the work is a relevant factor to set the prices of the tender appropriately or to decide not to submit a tender at all.

Factual and Legal Background of the Case

On 6 February 2025, the Advocate General provided his interpretation in case C-82/24 concerning a dispute over the guarantee period of a public contract in Czaika (Poland), the subject matter of which was the modernisation and expansion of a sewage sludge thermal treatment plant which required the installation of two recuperators.

The successful tenderer was a consortium of undertakings led by Veolia Water Technologies sp. z o.o. (hereinafter referred to as ‘Veolia’).

In particular, the contract contained a clause establishing a guarantee period of 36 months, which would start from the delivery of the completion certificate for the works (issued on 21 March 2013). This clause stipulated that for matters on which it is silent, the relevant provisions of Polish law, including the Civil Code, would apply.

According to Article 581(1) of the Civil Code relating to sales contracts – deemed applicable by some national courts – the guarantee period begins to run again from the moment of delivery of an item free from defects in place of the defective item or from the moment of the return of the item repaired.

On 26 September 2014 and 3 March 2015, the contracting authority notified Veolia that the recuperators had broken down.

In compliance with the guarantee obligation, Veolia replaced the faulty recuperators on 22 February and 28 April 2016.

On 27 November 2018, the contracting authority informed Veolia of a new breakdown of the two replacement recuperators, requesting their repair or replacement, but Veolia rejected this request, arguing that the guarantee obligation had been extinguished due to the expiry of the agreed-upon period, which was fully and precisely specified in the guarantee clause.

The disagreement between the parties led to two lawsuits before the Regional Court of Warsaw.

The controversial question is whether, despite the expiry of the guarantee period set out in the clause at issue, a new guarantee period had begun to run again from the time of delivery, by Veolia, of the replacement recuperators.

Question Referred for a Preliminary Ruling

In this context the Polish judge doubts whether the interpretation of the clause in question is compatible with the principles set out in Article 2 of Directive 2004/18/EC, applicable ratione temporis, (entitled ‘principles of awarding contracts’) according to which ‘contracting authorities shall treat economic operators equally and non-discriminatorily and shall act in a transparent way’. These principles are now enshrined in Article 18 of Directive 2014/24.

Consequently the national judge has referred to the Court of Justice the following question for a preliminary ruling:

‘Must the principles of transparency, equal treatment and fair competition referred to in Article 2 of Directive 2004/18 … be interpreted as precluding an interpretation of national law that would allow the provisions of a public procurement contract concluded with a consortium consisting of entities from different EU Member States to include an obligation that may indirectly affect the determination of the price contained in the tender submitted by that contractor, which obligation is not expressly provided for in the contract or in the tender documents, but arises from a provision of national law that does not apply directly to that contract, but is applicable by analogy?’

The Reasoning of the Advocate General

First, the Advocate General affirms that the principles laid down in Article 2 of Directive 2004/18 (equal treatment, transparency and proportionality) shall apply to an incident occurring during the performance of the contract.

In fact, the Court of Justice’s case-law shows that these principles (now set out in Article 18 of the current Directive 2014/24) are to be complied with at every stage of the life of the contract (see the judgment of 8 July 2021, Sanresa, C‑295/20, para. 63 and point 2 of the operative part; the judgment of 7 September 2021, Klaipėdos, C‑927/19, para. 90; and the judgment of 26 September 2019, Vitali, C‑63/18, para. 39).

At this point the Advocate General focuses on the application of the principle of transparency, closely linked to that of equal treatment, which has two declinations:

• a sufficient degree of publicity on the part of the contracting authority to enable, on the one hand, the opening up to competition and, on the other, the impartiality of the award procedure to be reviewed;
• drawing up all the conditions and detailed rules governing the award procedure in a clear, precise and unequivocal manner so that … all reasonably informed tenderers exercising ordinary care can understand their exact significance and interpret them in the same way (point 64).

The Advocate General notes that the Polish judge proposes the resolution of the question through a broader application of the principles established by the Court of Justice in the case Pizzo of 2 June 2016 (C-27/15), while acknowledging that this case does not concern the contract execution phase.

Specifically the case Pizzo is about the exclusion of a tenderer for failing to pay the contribution required for participation in the tender. This obligation was not expressly stated in the contract notice or in the specifications, but could be deduced from national rules of general application integrated into the tender documents by default (in Italian the so-called principle of ‘eterointegrazione’ of the competition rules).

On that occasion the Court ruled that: ‘… the principle of equal treatment and the obligation of transparency must be interpreted as precluding an economic operator from being excluded from a procedure for the award of a public contract as a result of that economic operator’s non-compliance with an obligation which does not expressly arise from the documents relating to that procedure or out of the national law in force, but from an interpretation of that law and those documents and from the incorporation of provisions into those documents by the national authorities or administrative courts. …’ (C-27/15, para. 51).

By transposing these principles to the present case, the Advocate General points out that it is for the referring court to assess if the interpretation of the guarantee clause was or was not reasonably foreseeable by a diligent operator.

This assessment is related to the operator’s knowledge of national law and the level of legal certainty which that law has to provide in the context of public procurement.

According to the Advocate General, the essential principles of transparency and legal certainty can only be secured if the terms of the contract allow all interested parties to understand their content and their scope. Furthermore, in this case, a distortion of competition could arise to the detriment of economic operators from other Member States relying on the wording of the guarantee clause.

As stated in the Opinion in Pizzo, it would be illogical for all contracting authorities to be obliged to specify in the tender documents the conditions required by generally applicable legislative provisions.

Notwithstanding, this argument cannot justify the acceptance of the application of contractual obligations, the foreseeability of which cannot reasonably be deduced from the wording of the contract, even when combined with those general legislative provisions which are indisputably applicable.

It is for the referring court to determine whether in this case the interpretation of the guarantee clause beyond its express wording, was acceptable, in order to discern whether the economic operator was in a position to be reasonably aware of the interpretation of the guarantee clause.

To this end, according to the Advocate General, the following elements should be taken into account:

1. a) there is no need to have recourse to general provisions of national law (and thus to the guarantee required for sales contracts) if the parties to the contract expressly agree on a specific guarantee period, specifying its duration;
2. b) the general provision of the Polish Civil Code at issue (i.e. that on the renewal of the guarantee period relating to contracts of sale), would not be applicable because it comes into play only where the guarantee clause is silent;
3. c) in the event of additional application of the Civil Code provision, the interpretation of Article 581(1) should be imposed on the basis of evidence that left no room for doubt on the part of a diligent and reasonably well-informed operator;
4. d)  the logic inherent in the guarantee provided in works contracts concluded between professionals is, from an economic perspective (in terms of risks and costs), different for that in sales contracts (usually conceived with the aim of protecting consumers). Therefore, the two different types of guarantees cannot be considered equivalent;
5. e) factors such as the physical presence of the company in the place of performance or its experience in the area of construction works could be taken into consideration. Similarly, it could be relevant if the interpretation given to the content of the guarantee clause by the contracting authority was sufficiently well known in the sector.

In light of the above, the Advocate General suggests that the Court answer the question referred for a preliminary ruling as follows:

‘Article 2 of Directive 2004/18/EC of the European Parliament and of the Council of 31 March 2004 on the coordination of procedures for the award of public works contracts, public supply contracts and public service contracts must be interpreted as not precluding the inclusion in a public works contract of a clause which, in order to establish the temporal scope of a guarantee obligation on the part of the contractor and for matters on which that clause is silent, refers to the provisions of the national civil code.

The principles of equal treatment and transparency laid down in Article 2 of Directive 2004/18 are not, however, compatible with an interpretation of that clause which, by extending the guarantee period beyond what was agreed by the parties, could not be foreseen by a reasonably well-informed and normally diligent contractor. It is for the referring court to determine whether that is the situation arising in this case’ (point 82).

Concluding Remarks

As is evident from the clear and unambiguous wording of the clause, the parties to the contract intended to regulate the duration of the guarantee period by applying the principle of negotiating autonomy (laid down in Article 353 of the Polish Civil Code).

As the Latin maxim goes: ‘in claris non fit interpretatio’ (Eng: ‘in clarity, interpretation is not done’).

Consequently it seems that the interpretation of the guarantee clause advocated by the contracting authority is not viable.

It is recalled that the fundamental principle of good faith must inspire the conduct of the parties not only in the negotiating phase of the contract, but also during its performance, including its interpretation.

Suggested citation