IT litigation lawyer in Paris: failed projects, court-appointed expert assessment, termination and quantifying loss.

Start by fixing the facts before choosing a remedy. A failed-project case answers three questions: what was meant to be delivered, what actually was, and who caused the gap. Gather the contract and its functional appendices, the successive schedules, the committee minutes, the tickets and the emails that record both the requests and the answers. Keep the delivered versions and test environments intact, because a modification or an uninstallation can compromise the examination of their initial state. The choice of remedy comes next: Article 1217 of the French Civil Code (Code civil) allows the creditor to suspend its own performance, to seek enforcement, to obtain a price reduction, to bring about termination or to claim damages, these remedies being cumulative where they remain compatible. The chronology must also show your own cooperation. In a software package dispute, the Lyon court of appeal rejected the complaints of a client that had stopped answering the publisher's reminders, holding that "While it is true that Val Software was subject to an enhanced obligation of best efforts, that obligation could only be met if the client answered its requests for improvement of the software" (our translation) (CA Lyon, 3e ch. A, 2 July 2026, No. 22/05916). The firm reconstructs this thread document by document before any letter to the opposing party.

When the cause of the failures is disputed and the evidence risks disappearing. Article 145 of the French Code of Civil Procedure (Code de procédure civile) authorises a measure of inquiry before any trial, on application or in urgent proceedings, if a legitimate reason justifies establishing or preserving evidence of facts on which the outcome of the dispute will depend; in the wording applicable since 1 September 2025, it leaves the applicant the choice between the court deciding the merits and the court of the place where the measure is to be carried out. That reason must be proved. The Court of Cassation recalls that "The assessment of the legitimate reason within the meaning of this provision falls within the sovereign discretion of the trial judge" (our translation) and approved a refusal of a measure based on mere suspicions with no specific fact (Cass. 2e civ., 10 December 2020, No. 19-22.619). Conversely, in an ERP replacement whose launch had been delayed, the urgent applications judge of the Paris economic activities court ordered an expert assessment, specifying that the measure "must be strictly limited to establishing or preserving evidence" (our translation) (TAE Paris, réf., 24 January 2025, No. 2024046137). Article 263 also reserves expert assessment for cases where a factual finding or a consultation would not suffice. If the judge grants an application for an expert assessment made before trial, the time limit for acting is suspended, then resumes from the day the measure was carried out, and may not then be less than six months (Article 2239 of the Civil Code).

The brief must target the points that are genuinely disputed, failing which the report will miss the mark. The judge appoints a technician to inform the court on questions of fact (Article 232 of the French Code of Civil Procedure): it is therefore for the parties to propose precise questions. In an integration project, the useful questions concern the state and conformity of the deliverables against the specifications, the causes of the delays, what each party was to supply, the attribution of the defects and the cost of a recovery. The urgent applications judge of the Paris economic activities court (tribunal des activités économiques) accordingly asked the expert to "state whether the deadlines as contractually set could or could not technically be met" (our translation), and to state which items the client was to hand over to allow the configuration work (TAE Paris, réf., 24 January 2025, No. 2024046137). Where quantification requires financial competence, the expert may obtain the opinion of another technician in a speciality distinct from their own (Article 278). This is no minor point: in the case decided by the Toulouse court of appeal, the assistant expert (sapiteur) appointed on the loss had been challenged by the claimant, which then refused to pay the deposit, so that the expert could not assess the loss (CA Toulouse, 2e ch., 25 November 2025, No. 23/02664). The firm drafts a proposed brief and defends it at the hearing.

The judge sets a deposit on account of the expert's fees and designates the party that must pay it into court, within the time limit the judge sets (Article 269 of the Code of Civil Procedure). Failing payment, the appointment lapses, unless extended or relief from lapse is granted for a legitimate reason; the proceedings continue, but the judge may draw any consequence from the abstention or refusal (Article 271). These consequences are real. In a bespoke development worth €810,000 excl. VAT, the Paris court of appeal noted that "since Finance Factory did not pay the fees called by the expert, the expert was unable to carry out the first assignment that was decisive for the court" (our translation), then relied on the client's private audit and on the project correspondence to confirm termination and order restitution of €480,000 (CA Paris, pôle 5 ch. 11, 16 October 2026, No. 22/07211). A refusal to pay the deposit can also turn against the claimant: the Toulouse court of appeal reminded a company that had refused to pay the deposit that "It is therefore for it to justify its loss and the direct causal link with the sole fault found against SA Orange" (our translation), and rejected its claims for lost customers and turnover (CA Toulouse, 2e ch., 25 November 2025, No. 23/02664). Before giving up an expert assessment for cost reasons, weigh this evidential risk.

It is useful, but rarely sufficient on its own. The judge may rely only on documents the parties have been able to discuss in adversarial proceedings (Article 16 of the Code of Civil Procedure). The Court of Cassation infers from this that, while the judge must examine a document properly produced, the judge "may not rely exclusively on a non-judicial expert report carried out at the request of one of the parties" (our translation); it so held in an inheritance dispute, but the rule applies to any report commissioned by one party alone (Cass. 1re civ., 15 January 2025, No. 22-21.949). A private audit must therefore be corroborated. In the Finance Factory case, the Paris court of appeal accepted the findings of the client's audit firm, which noted in particular the instability of the application, erroneous calculations, the absence of tests and incomplete documentation, because the provider's emails did not contradict them and the court-appointed expert assessment could not take place because of the provider (CA Paris, pôle 5 ch. 11, 16 October 2026, No. 22/07211). Conversely, a report made too late loses its force: the Lyon court of appeal denied any probative value to a report drawn up after the termination, when the client no longer had access to the software (CA Lyon, 3e ch. A, 2 July 2026, No. 22/05916). The firm has the audit carried out before termination and puts it, as soon as possible, to the other party's observations.

Yes, during the expert's operations and then before the judge, but on distinct grounds. During the assessment, the expert must take the parties' written observations into consideration, attach them to the opinion if the parties so request and indicate what follow-up was given to them; the expert is not required to take into account those filed after the deadline set, except for a serious and duly justified cause reported to the judge, and the last written observations must briefly restate the earlier ones, failing which these are deemed abandoned (Article 276 of the Code of Civil Procedure). These observations, known as dires, are the moment to discuss method, tests and attribution. After the report is filed, nullity of the report is governed by the regime for procedural acts (Article 175): it requires, in principle, proof of a prejudice caused by the irregularity (Article 114). The Toulouse court of appeal accordingly rejected the application of a telecoms operator that complained that the expert had not answered its observations, after noting that "The court notes that SA Orange does not specify what prejudice it suffered after the expert report was filed" (our translation) (CA Toulouse, 2e ch., 25 November 2025, No. 23/02664). The most effective challenge therefore often remains technical: showing, with documents, that the expert did not examine a decisive point, or that the conclusions do not follow from the findings. The firm prepares the observations as the meetings proceed rather than on the eve of the report.

Termination can always be sought from the judge (Article 1227 of the Civil Code), who may also grant the debtor a period of grace or award only damages (Article 1228). Notice is quicker but at the creditor's own risk: outside cases of urgency, it requires a prior formal notice expressly announcing termination, then a reasoned notice, and it is for the creditor to establish the seriousness of the breach when the debtor goes to court (Article 1226). The risk is concrete. The Lyon court of appeal confirmed termination at the sole fault of a client that had ended a software package contract with immediate effect, without formal notice or urgency, while the publisher was awaiting its answers (CA Lyon, 3e ch. A, 2 July 2026, No. 22/05916). The Court of Cassation specifies, in a consultancy dispute unrelated to IT, that a termination without serious non-performance is wrongful in itself: the court of appeal could not characterise it as merely abrupt, "from which it followed that the termination was unjustified and not merely abrupt" (our translation) (Cass. com., 29 January 2025, No. 23-17.795). If the creditor relies on a termination clause, termination requires, unless otherwise stipulated, an unsuccessful formal notice expressly mentioning the clause (Article 1225 of the Civil Code); this route remains distinct from judicial termination and from notice. The firm chooses the judicial route where seriousness is arguable, and reserves notice for documented failures.

No, and this is the main lesson of a white-label mobile application dispute. The client had paid a deposit of €62,640; the court of appeal had pronounced termination at shared fault and refused any restitution. The Court of Cassation quashed that judgment on the ground that "the acceptance of shared fault does not preclude restitution" (our translation), and required the judge to examine each party's share of responsibility and each party's loss before rejecting the claims for damages (Cass. com., 15 May 2024, No. 23-13.990). The same judgment contains a ruling unfavourable to the client: the complaint of failure to advise was rejected, because "the competence of Amarris enabled it to appreciate the exact scope of the technical characteristics of the goods and services supplied to it" (our translation) (Cass. com., 15 May 2024, No. 23-13.990). On remand, the Paris court of appeal held that "The fault committed by a contracting party giving rise to the termination of the contract does not preclude its right to restitution" (our translation), confirmed restitution of the €62,640, then allocated responsibility at 70% to the provider and 30% to the client (CA Paris, pôle 5 ch. 5, 12 February 2026, No. 24/09726). Holding against the client the delay in developing its interface and a termination without the formal notice required by the contract, the court ordered it to pay the provider €31,800 in damages, while awarding it €9,097.13, so that after set-off it remained a debtor for €22,702.87. Restitution and compensation are therefore calculated separately.

It all depends on the usefulness the services had before completion. If the solution was of interest only once fully delivered, each party returns what it received; if the services were useful as the contract was performed on both sides, nothing is returned for the period preceding the last service left without consideration, which is then termed résiliation rather than résolution (Article 1229 of the Civil Code). Restitution of a service is made in value, assessed as at the date it was supplied (Article 1352-8). In a caterer dispute unrelated to IT, the Court of Cassation set aside a refusal to return a deposit, the court of appeal having ruled so "although it noted that the services that were the subject of the contract had not been performed" (our translation) (Cass. com., 18 January 2023, No. 21-16.812). Applied to IT projects, the rule leads to full restitution where nothing usable was delivered: the Paris court of appeal ordered restitution of €32,628.01 for management software presented as turnkey, left unfinished after a partial data migration (CA Paris, pôle 5 ch. 11, 28 November 2025, No. 23/12938), and of €480,000 for a bespoke development never delivered on the terms of the contract (CA Paris, pôle 5 ch. 11, 16 October 2026, No. 22/07211). The firm first characterises the economics of the contract, licence, integration or maintenance, because it governs the extent of restitution.

Item by item, distinguishing what falls under restitution from what falls under compensation. A defaulting debtor answers for the loss it caused the creditor and the profit it deprived it of (Article 1231-2 of the Civil Code), but, except in cases of gross negligence or wilful misconduct, only for the damage that could have been foreseen when the contract was concluded (Article 1231-3). Gross negligence remains exceptional: the Toulouse court of appeal ruled it out, recalling that "gross negligence is characterised by conduct of extreme seriousness bordering on wilful misconduct" (our translation) (CA Toulouse, 2e ch., 25 November 2025, No. 23/02664). The usual items are the extra cost of recovery by another provider, keeping the old system running, licences paid for without use and operating loss. To have the obligation performed by a third party at the debtor's expense, the creditor must first give formal notice, then act within a reasonable time and at a reasonable cost as well (Article 1222 of the Civil Code). Lost profit is measured in margin, not in turnover: on remand after cassation, the Paris court of appeal held that "The exploitation of the licences is a profit of which Smartpush was deprived and whose compensation equals the margin loss likely to have been made" (our translation), applying a 50% margin weighted by the client's share of responsibility (CA Paris, pôle 5 ch. 5, 12 February 2026, No. 24/09726). The firm builds the quantification with the accounting documents and, if needed, a chartered accountant.

They can, provided they are justified. In the mobile application dispute, the Paris court of appeal awarded the client €1,250.97 for the time its employees devoted to the project, on a count justified by the number of people involved (CA Paris, pôle 5 ch. 5, 12 February 2026, No. 24/09726), after applying its share of responsibility. Conversely, in the turnkey management software dispute, the Paris court of appeal ordered restitution of the price while rejecting the €10,000 claimed for the mobilisation of teams, the client having claimed "without however producing supporting documents enabling the reality of the corresponding consideration to be assessed" (our translation) (CA Paris, pôle 5 ch. 11, 28 November 2025, No. 23/12938). In the Finance Factory case, the same chamber rejected a claim of €349,182 for internal and external costs incurred to no purpose, noting that the client had subsequently been able to develop its application without justifying the price or the expenses incurred (CA Paris, pôle 5 ch. 11, 16 October 2026, No. 22/07211). It added that "the costs it also incurred to establish proof of its loss fall to be assessed under Article 700 of the Code of Civil Procedure" (our translation), that is, a sum fixed in equity for the costs of the proceedings (Article 700 of the Code of Civil Procedure). To avoid such rejections, you need timesheets contemporaneous with the project, the identity of the people assigned, their salary cost and proof that this time was lost rather than reused. The firm gathers these items as soon as the dispute opens.

The judge accepts the profit of which the breach deprived the company, provided the causal link is demonstrated. A growth projection is not enough. In the case decided by the Toulouse court of appeal, the company claimed that it had expected growth of 12.11% and had suffered a decline of 4.89%; the court held that the link between the slowdowns of its business software and that development was not established, other causes appearing in the documents (CA Toulouse, 2e ch., 25 November 2025, No. 23/02664). Where the hoped-for result remains uncertain, the loss takes the form of a loss of chance. The Court of Cassation holds, in a share-transfer dispute unrelated to IT, that "compensation for a loss of chance must be measured by the chance lost and cannot be equal to the advantage that the chance would have provided had it materialised" (our translation) (Cass. com., 12 March 2025, No. 23-16.460). A missed commercial launch, a lost client contract or a cost saving not achieved are lost profit where their realisation is established, and loss of chance where it remained uncertain: in the latter case only, compensation is measured by the chance lost, and not by the whole gain. The firm bases this assessment on comparative accounting data, on existing commercial commitments and, where the brief allows, on the opinion of a financial assistant expert (sapiteur) appointed in the expert assessment.

Yes. A provider that suffers an unjustified termination can claim the invoices that have fallen due, then compensation for the loss suffered and the profit lost. The Court of Cassation set aside a judgment that had limited compensation to the abrupt nature of the termination, although no serious non-performance was established, "from which it followed that the termination was unjustified and not merely abrupt" (our translation) (Cass. com., 29 January 2025, No. 23-17.795). In the mobile application dispute, the Paris court of appeal, having set the client's share in the termination at 30%, notably because of a termination without the contractual formal notice, awarded the provider €31,800 for the deposit excl. VAT that was used and then returned and for its lost margin over three years of licences (CA Paris, pôle 5 ch. 5, 12 February 2026, No. 24/09726). The Lyon court of appeal confirmed termination at the sole fault of a client that had stopped answering the publisher's reminders before terminating with immediate effect (CA Lyon, 3e ch. A, 2 July 2026, No. 22/05916). The provider's defence rests on its reminders, its priced proposals, incident tracking and proof of out-of-scope requests. The firm also checks the limitation-of-liability clause and the caps provided in the contract, which can work in both directions.