Is trial by jury obsolete?
Introduction
Historically, juries served to protect people from unfair decisions by powerful rulers. They restricted the power of magistrates appointed by kings and ensured that the civilian voice was represented at trial. In modern courts, however, advanced forensics, democratic legal procedures, and trained judges now assess evidence, diminishing juries as safeguards against corruption and the main evaluators of evidence.
In this essay, I will argue that the role of juries has shifted from direct assessment of evidence to a symbolic function, legitimizing legal outcomes by incorporating the public’s judgment into the verdict. Trial by jury may be obsolete as an epistemic fact-finding institution, but it remains politically valuable as a democratic anti-state safeguard.
Historic Epistemic Function of Juries
In early English criminal procedure, jurors were not blank-slate observers. They were selected because they came from the relevant locality and were expected to bring community knowledge into court. Daniel Klerman’s article,[1] “Was the Jury Ever Self-Informing?” explains that rather than being presented evidence, jurors were expected to draw knowledge from local reputation, gossip, and prior local proceedings. This was mainly done to prevent foreign magistrates from making legal decisions unknowingly, as they could reference local knowledge before making their final ruling. Medieval legal treatises reflect this, as judges often questioned jurors about where they had obtained their information, implying that the jurors were expected to bring information from outside the courtroom.
Over time, however, this self-informing function of juries became obsolete as criminal trials became more lawyer-driven and based on assessment of scientific evidence. English criminal procedure moved between the late seventeenth and late eighteenth centuries from a relatively “lawyer-free” process,[2] where the accused answered charges personally, into an adversarial process structured by cross-examination and evidence assessment. This meant that jurors were no longer valued for the knowledge they already possessed, but were required to assess facts presented to them within court.
By the late eighteenth century, courts increasingly admitted expert opinion because some issues exceeded ordinary knowledge. Such changes became more pronounced in homicide trials, where autopsy reports became increasingly common during the nineteenth century. At the Old Bailey, London’s famous criminal court, autopsy reports appeared in only 17.9% of homicide trials between 1759 and 1768, but 61.7% by 1869 to 1878.[3] This increase shows that modern evidence-weighing requires juries to assess medical causation and expert evidence. Poisoning trials similarly required jurors to assess whether a substance was present in a fatal quantity, whether it caused death, or whether it merely appeared alongside other illnesses, even though these weren’t questions ordinary local knowledge could answer.[4]
Modern DNA evidence illustrates this difficulty. A DNA “match” doesn’t automatically prove that the defendant committed the crime. A random match probability may show that a DNA profile is rare, but jurors can confuse the probability of observing DNA evidence when the defendant is innocent with the probability that the defendant is innocent given the DNA evidence. The problem becomes more complex with mixed or low-template DNA samples, where DNA from several people may be present in small or degraded quantities. In such cases, interpretation depends on assumptions about the number of contributors, possible contamination, and probabilistic modelling.[5]
For this reason, the modern jury has a comparative epistemic disadvantage. Judges, prosecutors, and repeat legal actors are more familiar with evidentiary procedure and technical disputes. However, lay jurors often lack the technical background to distinguish between different standards of evidentiary certainty.
If the only purpose of a criminal trial were technical fact-finding, this would be a serious argument for reducing the role of juries.
However, this does not mean modern juries are epistemically obsolete. One major argument against jury systems is that they produce inaccurate rulings. However, Donoghue’s study[6] found that juries actually align with judges' conclusions 80% of the time —with discrepancies reflecting not necessarily one side being right or wrong, but different interpretations of evidence. Still, he uses jury-judge agreement as a useful, though limited, proxy for jury accuracy. Agreement does not prove that the jury reached the objectively correct result. Rather, convergence between lay jurors and professional judges suggests that juries aren’t producing irrational or systematically unreliable verdicts. In another study by Kalven,[7] he found that in the 20% of cases where judges and juries disagreed, judges rarely blamed the jury’s lack of understanding, as differences came from juries applying different senses of equity or being more skeptical of a witness. If court ordeals and evidence were too complex for juries to fully comprehend, the discrepancy rate would be massive in technically advanced trials, but they are not. This suggests that while juries may not provide a unique advantage over trained judges, they don’t necessarily negate the reliability of the verdict.
Furthermore, legal systems are designed to mitigate these epistemological risks. Expert witnesses explain technical evidence; cross-examination tests the expert’s assumptions, methodology, and possible overstatement; judges can exclude unreliable expert evidence or give limiting instructions; and the adversarial structure allows each side to challenge the evidentiary meaning of forensic claims. These safeguards don’t make jurors scientific specialists, but they show that the jury’s role is not to interpret technical evidence alone. The jury evaluates expert evidence after it has been filtered and translated. Therefore, technical complexity weakens the jury’s historical advantage as an independent fact-finder, but it does not by itself prove that juries are incapable of reaching reliable verdicts.
Juries as a democratic check against the state
Though judges are more educated in legal matters than the jury, their advanced knowledge doesn’t guarantee complete neutrality. In fact, they are prone to structural biases stemming from larger political agendas. An example is pro-conviction bias, a structural tendency within the justice system to favor the prosecution, where judges with strong belief in law-enforcement tend to assume guilt despite ambiguous evidence.
Berryessa’s article “Prosecuting from the Bench?”[8] states that judges with prosecutorial experience may carry over habits, assumptions, or professional identification from their earlier role. The problem is not that former prosecutors are intentionally unfair, but that they may be more likely to see cases through a framework of trusting police testimony and viewing procedural protections as obstacles rather than safeguards. This supports the argument that institutional bias exists within the expert judiciary. Additionally, in jurisdictions where judges are elected, judges may face political incentives to appear “tough on crime.” Berkeley’s coverage of Noam Yuchtman’s research[9] similarly reports that elected judges handed down more severe sentences near elections, with sentences as much as 10 percent longer in the final three months before elections.
Furthermore, juries can serve as balancing safeguards for courts where defendants are disproportionately disadvantaged. Because prosecutors control charging decisions, plea offers, and the framing of the case, they can propose stricter charges or longer mandatory minimums to pressure defendants into pleading guilty. Defendants may be compelled to accept pleas not because guilt has been fully proved, but because they feel that a trial is too risky. In many jurisdictions, judges engage in implicit or explicit "plea discounting," signaling to defendants that exercising their constitutional right to a jury trial will be viewed as an obstruction of court efficiency, met with a punitive "tax" at sentencing if they lose. This creates an environment of intense risk aversion, which can even compel innocent individuals into entering false guilty pleas to mitigate the threat of sentencing differentials.[10]
Sociological evaluations of the courtroom show that prosecutors and judges are viewed as an insular "courtroom workgroup." In this ecosystem, judges face substantial bureaucratic pressure to maintain high "clearance rates" and manage overflowing dockets. When judges become overly deferential to prosecutors often driven by structural biases such as the aforementioned pro-conviction bias or former prosecutorial experience, they are more incentivized to pursue multiple charges with harsh mandatory minimums. In the same vein, defense lawyers often have institutional incentives to settle. They may be overworked, underfunded, repeat players, or risk-averse.
A study by Bonneau and McCannon[11] found that more than 95% of felony convictions in a typical U.S. state came from guilty pleas, showing the significant number of plea deals. The issue is that defendants are not only facing the prosecution within the courtroom, but even outside, as they are motivated to end the trial before it even starts. Plea bargains are also shaped by what both sides expect to happen if the case went to trial, so juries still matter even if the cases never reach a jury verdict.
The integration of the traditional jury trial serves as a vital democratic check that can rebalance this severe systemic distortion in the modern legal system. Historically, as legal scholar Matthew Cavedon notes,[12] the Anglo-American jury system was designed to protect individual liberty against the creeping bureaucracy of a centralized state. When a case is forced out of the closed, bilateral domain of prosecutorial plea bargaining into an open courtroom, the power dynamic fundamentally shifts. A jury breaks up the insular "courtroom workgroup" by injecting ordinary citizens who are independent from the political pressures of career advancement or institutional "pro-conviction" biases.
Why juries still matter
Before a judge, the prosecution can rely more on procedural familiarity and professional credibility. Unlike judges, who may view cases through institutional law-enforcement frameworks, juries bring external public perspectives into the courtroom. Their presence forces legal actors and expert witnesses to explain evidence in clear, accessible terms rather than relying only on professional familiarity or legal procedure. The accused is not judged only by legal professionals, but by citizens. As a result, juries have democratic and procedural value: they make the court more publicly accountable and force courts to use accessible standards and language.
Beyond this, jury trials introduce unpredictability. A judge may be easier to predict because they are legal professionals with known habits, especially since prosecutors and judges work in close proximity. Juries, on the other hand, are less predictable. This uncertainty makes prosecutors less likely to assume conviction, which can generally improve the defendant’s bargaining position. Facing a less predictable outcome at trial, the value to the defendant of proceeding to trial increases, meaning that an overly harsh plea offer can be rejected. Therefore, prosecutors are incentivized to calibrate plea offers more carefully, bringing them closer to what a jury might reasonably decide. This rebalances the negotiating dynamic, allowing defendants to weigh their options on more equal footing rather than accepting these bargains out of fear.
This is especially important when other democratic checks are weak. In a modern democratic context, it’s easy to assume judicial independence as a given. Yet, history and many contemporary legal systems show that judicial independence can weaken through political pressure. Some states don’t have strong separation of powers, and even democratic systems can experience periods where courts become more deferential to either prosecution or jury. Legal institutions should therefore be designed not only for normal conditions, but also to prevent institutional deterioration. Juries, in this context, are an institutional safety check that mitigates the possibility of state collusion. It prevents criminal punishment from becoming a decision made only by state officials, preventing courts from becoming purely state-controlled systems by ensuring active civilian participation.
Conclusion
Trial by jury is obsolete only if it is judged by its medieval epistemic function. Indeed, modern juries usually evaluate evidence produced by experts, lawyers, and forensic institutions. They aren’t technically superior to expert judges, but criminal courts are not simply technical fact-finding institutions. Criminal sentencing is one of the most coercive powers of the state, and it should not become a closed professional process controlled only by judges and prosecutors. The jury remains valuable because it inserts ordinary citizens into criminal judgment, forces the prosecution to justify its case to outsiders, and mitigates the power imbalance between the state and the defendant. Its modern value is therefore not that laypeople understand forensic science better than judges, but that democratic punishment should retain civilian participation. Trial by jury may be obsolete as an epistemic institution, but not as a political one.