Conflict and Tort Law

Last registered on April 24, 2026
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Pre-Trial

Trial Information

General Information

Title
Conflict and Tort Law
RCT ID
AEARCTR-0018391
Initial registration date
April 17, 2026

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
April 24, 2026, 8:44 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Country
Czechia
Region
Prague

Primary Investigator

Name
Sergio Mittlaender
Affiliation
FGV Direito SP
Contact Primary Investigator

Other Primary Investigator(s)

Additional Trial Information

Status
Completed
Start date
2019-01-21
End date
2021-11-05
Keywords
Lab
Additional Keywords
Law & Economics, Tort Law
JEL code(s)
K13, C91
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Economic models of tort law explain how liability deters accidents, but not how it pacifies conflict. This article incorporates victims’ aggrievement, arising from harm and blame, and the behavioral responses that generate socially costly conflict into the model. Legal remedies shape injurers’ ex ante choices and victims’ ex post responses. Compensation acquires an independent welfare justification, the comparison between negligence and strict liability changes, negligence standards may track social norms rather than the Hand formula, and punitive damages, sanctions, and injunctions may improve welfare. A laboratory experiment shows that blame and harm each cause retaliation, while compensation substantially reduces it.
External Link(s)

Registration Citation

Citation
Mittlaender, Sergio. 2026. "Conflict and Tort Law." AEA RCT Registry. April 24. https://doi.org/10.1257/rct.18391-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
Intervention (Hidden)
Intervention Start Date
2019-01-21
Intervention End Date
2021-11-05

Primary Outcomes

Primary Outcomes (end points)
retaliation
Primary Outcomes (explanation)
points invested in costly punishment by the victim, at a rate of 1:4.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The experiment uses a between-subject design with three treatments: no liability, negligence, and strict liability. Participants are assigned to the role of injurer or victim and remain in that role throughout the experiment. They play a game in which injurers choose a level of care that reduces the victim’s loss if an accident occurs, and victims can retaliate against injurers through costly punishment. The treatments differ in the legal consequences of an accident. Under no liability, victims bear the loss. Under negligence, compensation is owed only if the injurer failed to meet the due-care threshold. Under strict liability, compensation is always owed when a loss occurs. In all treatments, victims can punish injurers at a cost. The experiment has two stages. First, subjects play a one-shot interaction, and victims’ punishment choices are elicited for all contingencies using the strategy method. Second, subjects are rematched with a different partner and play 19 repeated rounds in the same treatment, without the strategy method.
Experimental Design Details
Randomization Method
Treatment conditions were assigned ex ante at the session level via pre-programmed session treatments. Participants enrolled in the sessions without being informed of the assigned treatment. Within sessions, the computer randomly assigned participants to the role of injurer or victim
Randomization Unit
Subjects and session
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
18 experimental sessions
Sample size: planned number of observations
336 subjects
Sample size (or number of clusters) by treatment arms
6 sessions and 112 subjects per treatment arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
Yes
Intervention Completion Date
November 05, 2021, 12:00 AM +00:00
Data Collection Complete
Yes
Data Collection Completion Date
November 05, 2021, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
18 experimental sessions
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
336 subjects
Final Sample Size (or Number of Clusters) by Treatment Arms
114 subjects in the no liability treatment, 114 subjects in the negligence treatment, and 108 subjects in the strict liability treatment
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials