MCAI Lex Vision: Rule Without Reason, Why Antitrust Courts Need Simulation Before They Can Balance
Commentary on Carrier & Lemley, "Rule or Reason?"
I. Introduction: The Disappearing Act of Legal Foresight
Michael Carrier and Mark Lemley’s article "Rule or Reason? The Role of Balancing in Antitrust Law," Notre Dame L. Rev. (forthcoming 2025). exposes a silent crisis in U.S. antitrust doctrine: the disappearance of actual balancing in the application of the rule of reason.
While the burden-shifting framework is routinely applied, the core function of weighing anticompetitive harms against procompetitive benefits has nearly vanished. Courts dispose of 97% of rule of reason cases at step one, leaving the balancing step to a theoretical ghost. Carrier and Lemley’s empirical insight is clear: we have built a regime of rules without reason, shortcuts without foresight.
MindCast AI LLC (MCAI) offers a commentary not just on the legal ramifications of this trend, but on its broader implications for decision-making and institutional integrity. Our core claim is simple: courts lack the tools to perform balancing because they lack the ability to simulate the outcomes of competing arguments. We believe simulation should supplement—not replace—judicial reasoning.
II. The Shortcut Problem: When Rules Replace Judgment
At the heart of Carrier and Lemley’s critique is a judicial impulse to avoid complexity. Rather than embrace the economic sophistication that the rule of reason presupposes, courts have constructed a legal architecture that disposes of cases at the earliest possible stage. This has transformed the rule of reason into a triage mechanism, not a reasoning framework.
The article meticulously traces how the courts, especially following Amex and Alston, have allowed a three-step framework (anticompetitive harm, procompetitive justification, less restrictive alternative) to displace the necessary fourth step: actual balancing. In doing so, courts conflate procedural sufficiency with substantive truth.
MCAI frames this as a loss of interpretive integrity. When courts cut off analysis before consequences are assessed, they forfeit their institutional mandate to weigh competing outcomes. The solution is not more formalism but better tools—especially tools that help surface the long-term impact of contested economic conduct.
III. Simulation as a Tool for Balancing
MCAI proposes a clear solution: courts should integrate simulation to support the balancing step. This is not abstract. A simulation model would:
Ingest structured data on market behavior (e.g., pricing, innovation rates, user lock-in)
Model competing outcomes: one pathway assuming the challenged conduct is allowed; the other assuming it is prohibited
Project effects over time (e.g., on pricing, market entry, innovation, consumer choice)
Offer comparative insights to inform judicial balancing
Courts could access these tools via third-party simulation firms, neutral academic panels, or government-authorized technical advisors. Simulations would be filed as part of expert testimony, reviewed under existing evidentiary standards, and subjected to cross-examination and adversarial scrutiny.
Judges and law clerks would require minimal technical training—akin to the way courts already evaluate econometric models or complex patent claims. To ensure transparency and due process, each simulation must be auditable, based on disclosed assumptions, and challengeable by opposing counsel.
Simulations would not determine outcomes. They would visualize plausible futures, allowing the court to consider long-term implications alongside direct effects. In this role, simulation serves as an evidentiary aid—not a substitute for judgment.
IV. The Institutional Stakes
What Carrier and Lemley reveal is more than doctrinal drift—it is a quiet erosion of legal foresight. The judiciary has outsourced reason to rule, foresight to form. MCAI forecasts three core risks if the trend continues:
Blind Spots in Platform Markets: Courts will keep missing cross-market harm signals (e.g., anti-steering provisions) because their tools don't surface multi-channel effects.
Procedural Paralysis: The burden-shifting shortcut will become the endgame. Courts will filter out complexity rather than interpret it.
Public Distrust: As courts legitimize conduct that looks anti-competitive to markets and the public, trust in legal enforcement will erode.
Simulation doesn’t replace judgment. It enriches it. A well-calibrated simulation allows courts to fulfill the original vision of the rule of reason: reasoned weighing, not shortcut screening.
V. Scope, Limits, and Legal Integration
Simulation is not a panacea. Some antitrust disputes, particularly those hinging on clear textual interpretation or where market effects are immediate and well-understood, may not benefit from modeling. Simulation should be prioritized for complex platform cases, multi-sided markets, or policy settings with deferred impact (e.g., innovation suppression, lock-in effects).
To avoid over-reliance, courts must:
Treat simulations as advisory, not determinative
Insist on cross-model validation when available
Appoint independent reviewers or amicus technologists in high-impact cases
Allow appellate review to question simulation validity, not just procedural use
Simulations would fit within current rules of evidence as demonstrative exhibits or expert interpretations of economic data. Courts could request assistance through existing Federal Rule of Evidence 706 (court-appointed experts) to ensure balanced understanding.
In short, integrating simulation into antitrust reasoning is a matter of procedural adaptation—not doctrinal overhaul. The infrastructure for this evolution already exists.
VI. Conclusion: Toward Better Judgment, Not Just Better Rules
Carrier and Lemley are correct: the rule of reason has become a rule without reason. But the remedy is not merely to reinstate balancing as doctrine—it’s to make balancing practical.
MCAI proposes a simulation-based support system that models outcomes, clarifies tradeoffs, and surfaces risks and benefits in ways a court can meaningfully assess. The law’s job is not to avoid hard questions but to equip itself to answer them.
With simulation frameworks in place—guided by evidentiary safeguards and judicial oversight—the judiciary can restore what the rule of reason was meant to do: reason through conflict, not discard it.