Truck Cartel Appeals and the Spanish Supreme Court’s Self-Inflicted Docket Crisis

Beyond mediation: the deeper costs of the Supreme Court’s drive to standardize truck cartel damages litigation.

Voluntary in form, coercive in tone

The recent non-jurisdictional agreement of the Spanish Supreme Court on pending truck cartel appeals should not be mistaken for a genuine turn to mediation. Formally, the Court merely proposes referral to mediation. In substance, however, it is doing something rather different: it is trying to convert the predictability generated by its own case law into settlement pressure. The message to the parties is clear enough. After years of rulings on these appeals, they already know -more or less- how most of them will end; insisting on a judgment rather than a consensual solution may therefore have consequences in legal costs. Voluntary in form, coercive in tone, the agreement is less an endorsement of mediation as a suitable form of dispute resolution than a managerial response to a mass of repetitive appeals the Court no longer wishes to decide one by one.  It is an extraordinary institutional response trying to manage an impossible docket.

That is understandable, but not merely technical. The Court is plainly overwhelmed. By the end of 2025, the Civil Chamber had 27,864 pending appeals, around 60% of them linked to mass litigation, and truck cartel cases represented a significant share of that burden. The Court itself says, in essence, that after three years of rulings and 171 judgments on the merits (available in CENDOJ), only marginal novelties remain. What is being presented as mediation is therefore better understood as an attempt to stop industrial-scale repetition by pushing the parties towards closure. Seen in that light, the agreement is interesting not because it reveals a judicial faith in mediation, but because it amounts to an institutional confession. The Supreme Court is now trying to contain a mass of appeals that it helped generate.

The broader context is by now familiar. Truck cartel litigation in Spain has long ceased to resemble ordinary bilateral civil litigation. It has instead become a form of de facto mass adjudication, conducted through thousands of individual claims but shaped by repetition, procedural routinization and the progressive standardization of judicial responses (see Almacén de Derecho 24/2/26). By March 2026, there had already been 171 Supreme Court judgments and 5,880 appellate judgments in truck cartel damages litigation, with appeals resolved concerning some 35,000 cartelized vehicles. Yet the litigation remained highly atomized: 17.5% of cassation appeals concerned a single truck, and in 45% of Supreme Court appeals the amount in dispute was below €15,000. The “mediation” initiative is therefore not an isolated procedural curiosity. It is the Court’s latest attempt to manage a form of mass litigation that ordinary civil procedure, and perhaps cassation itself, were never designed to absorb.

The Court’s own role in the flood of appeals

The current flood of truck cartel appeals is not simply the product of claimant opportunism, repeat-player litigation strategies, or the structural limitations of Spanish civil procedure. It is also, to a significant extent, the result of the Supreme Court’s own earlier choices.

In its truck cartel case law, the Court did not confine itself to settling points of law (see Kluwer Competition Blog 6/7/23 and Kluwer Competition Blog 16/5/24). It did more than clarify the conditions for judicial estimation, the allocation of the burden of proof, or the legal framework governing damages actions. It also stepped into the appraisal of evidence, correcting appellate courts that had accepted claimant expert reports and imposing a more standardized approach in the name of equal treatment.

That move had an obvious consequence. Once the Supreme Court signaled that the treatment of economic expert evidence was open, in practice, to cassation review, it became entirely rational for litigants to keep appealing. If appellate courts could be corrected not only on legal issues but also on the persuasiveness of the expert material before them, then each case retained at least the appearance of being individually reviewable.

That is why the present overload should not be presented as if it had simply descended on the Court from outside. The Court helped create the conditions for it. Having opened the door to large-scale review of evidentiary assessment in the name of uniformity, it can hardly be surprised that thousands of litigants tried to walk through it. In that sense, the Court now reaps what it sowed.

From law-unification to de facto third instance

The problem, moreover, is not just that the Court reviewed evidence. It is that, in doing so, it brought cassation very close to functioning as a de facto third instance in mass litigation.

To be fair, the Supreme Court was responding to a genuine problem. Truck cartel litigation had produced striking divergences in outcomes across materially similar cases, and the pressure to bring some order and predictability to this mass of claims was understandable. In that setting, an appeal to equality, consistency and legal certainty had obvious force.

But the Court did not pursue those objectives only by laying down legal doctrine. It also sought to standardize outcomes by revisiting how lower courts had assessed the claimant’s economic evidence. That was the more consequential step. Equality was no longer being pursued simply through the clarification of legal rules, but through centralized correction of evidentiary appraisal.

That is why the Court’s intervention cannot be described as ordinary cassation in any straightforward sense. Once a higher court begins to tell appellate courts not merely what legal test to apply, but also that they were wrong to find a particular expert report persuasive, cassation starts to function, in practice, like a further appellate layer. In the context of mass litigation, that move is especially significant. It transforms a court meant to settle questions of law into a body drawn into the serial supervision of case-by-case adjudication.

Raising the bar for expert evidence

That institutional shift had a further cost. Once the Court chose to reverse appellate judgments that had accepted claimant expert evidence, it could do so coherently only by adopting a demanding standard of what counts as a persuasive report. Otherwise, the basis for treating those appellate decisions as unreasonable would have been much weaker.

This is where the Court’s strategy becomes problematic beyond questions of docket management. The issue is not simply that some claimant reports were found unconvincing. It is that the standard of persuasion may have been pitched too high for the realities of competition damages litigation, where quantification is often difficult, imperfect and necessarily approximate. More importantly, this approach sits uneasily with the Court’s own earlier case law. In Sugar Cartel Damages I, the Court had indicated that it was not enough for the defendant simply to criticize the claimant’s expert report; it should also offer a better-founded alternative quantification. In the truck cartel rulings, however, the Court rejected claimant reports as insufficiently convincing while nonetheless moving directly to a standard judicial estimate. That shift is significant. It suggests a more demanding attitude towards claimant evidence, without a corresponding insistence that the defendant provide a more persuasive substitute.

That matters because judicial estimation is supposed to operate as a safety valve. It exists for situations in which harm is real but precise quantification cannot reasonably be expected. But if the threshold for accepting party expert evidence becomes too demanding, judicial estimation ceases to be a subsidiary corrective and starts to become the default outcome. The practical message is clear enough: even a serious economic report may still fail to pass muster, not because it is worthless, but because the court now expects too much from it.

The implications are not confined to truck cartel litigation. If the lesson drawn from these cases is that claimant expert evidence will be examined under an exceptionally exacting standard, while judicial estimation remains readily available as a fallback, the resulting evidentiary model may affect private enforcement more broadly. The danger is that a mechanism designed to ease proof where quantification is difficult ends up discouraging serious investment in proof altogether. If that becomes the operative standard, judicial estimation stops being a subsidiary tool and starts becoming the expected destination. That risk is compounded by the Court’s appeal to equality.

The costs of equal estimation

In the truck cartel case law, equality seems to mean that materially similar claims should converge on the same judicial estimate of harm, even where claimants have relied on different expert reports and made different evidentiary effort. From the standpoint of consistency, that may be understandable. From the standpoint of evidentiary policy, it is much harder to defend.

In trying to standardize outcomes, the Court may also have inadvertently standardized skepticism. If claimant expert reports are subjected to a demanding threshold and the likely fallback is the same judicial estimate anyway, then the incentive to invest in better proof is inevitably weakened. Why incur the additional cost of improving an expert report if, in the end, the court is likely to reject it as insufficiently convincing and move to the same estimate it would have reached in a weaker case?

There are already signs that this logic may spill beyond the truck cartel. If, as recent milk cartel judgments of the Barcelona Court of Appeal seem to suggest (ES:APB:2025:11839), courts begin to converge on a standard percentage despite differences in the expert reports relied on by claimants, the broader lesson is troubling: what is being normalized is not merely judicial estimation, but a model in which differences in evidentiary effort make little practical difference. What emerges, in other words, is a form of downward egalitarianism.

That is the deeper problem with the Court’s version of equality. Equality should not mean that all claimants receive effectively the same estimate regardless of the quality of the evidence they bring. What is especially troubling is the combination of a demanding standard of proof and a stable fallback estimate. Together, they distort litigation incentives: claimants are given weaker reasons to invest in better expert evidence, while courts are encouraged to treat judicial estimation as the real center of gravity. If judicial estimation becomes both uniform and relatively low, infringers face a predictable and limited downside, while claimants have little reason to improve their proof. That is roughly where case law now stands: across the 171 Supreme Court truck cartel judgments deleivered so far, the average award is about €3,205 per truck, plus interest, broadly reflecting the Court's now familiar 5% benchmarck. That iss a poor equilibrium from the standpoint of both the compensatory and the deterrent effect of damages actions.

Why this matters beyond trucks

The truck cartel is exceptional in scale, but the structural dilemma it reveals is not. The Supreme Court’s recent non-jurisdictional decision can also be read as an implicit acknowledgment that the Spanish system still lacks an adequate procedural framework for dealing with mass antitrust damages litigation. When mass private enforcement is channeled through fragmented individual litigation, higher courts face a difficult choice. They can confine themselves to settling the legal framework and tolerate some variation below, or they can pursue equalized outcomes case by case and risk turning themselves into bottlenecks.

The difficulty is not just that there are many cases. It is that the system has no satisfactory procedural vehicle for dealing with thousands of highly repetitive claims while preserving transparency, review and doctrinal coherence. When that structural deficit is combined with a Supreme Court willing to standardize outcomes through case-specific correction, the result is almost bound to be pathological: mass litigation below, mass cassation above, and mounting pressure to replace adjudication with increasingly managerial forms of case disposal.

Conclusion

The recent non-jurisdictional decision proposing referall to mediation should not be read simply as an innovative recourse to mediation. It is also an institutional confession. The Supreme Court is trying to escape a role it helped create for itself. By going beyond law-unification and into the correction of evidentiary assessment in truck cartel litigation, it helped turn these claims into a model of mass cassation. In doing so, it not only produced a self-inflicted docket crisis; it may also have sent a damaging signal for private enforcement more broadly, namely that substantial investment in expert evidence will often make little practical difference because judicial estimation will do the decisive work anyway. That is a troubling legacy. The Court now reaps what it sowed. Unless Spanish procedure develops better tools for handling mass competition damages actions, the same cycle may well repeat itself in future waves of private enforcement.

Disclaimer: The contributor serves as academic consultant of CCS Abogados, the law firm representing the largest number of claimants in Spain. The views and opinions expressed in this post are his own, and do not necessarily reflect the position of CCS.