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The Jury

G. Alexander Nunn, The Jury in Nunn on Evidence (2025), available at https://nunn.law/the-jury. | View history

The jury is one of the most venerated and, at times, debated institutions in the legal system. This exploration is foundational to understanding how evidence operates within the trial process. The system entrusts a panel of ordinary citizens with the profound responsibility of determining what happened in a case, a task that underpins the very legitimacy of judicial outcomes. While other chapters explore the intricacies of jury selection, the precise language of instructions, the dynamics of deliberation, and the rules governing juror testimony about their verdicts, the purpose here is to dissect the jury’s core function: to serve as the exclusive arbiter of facts.

Key Overview: The Jury’s Exclusive Dominion Over Factual Determinations

At the very heart of the American trial system, particularly where a jury is empaneled, lies the principle that the jury is the ultimate finder of fact. This isn’t merely a ceremonial role; it is a constitutional and deeply entrenched power. What this means, in practical terms, is that the jury is tasked with sifting through all the testimony, documents, and other forms of evidence that the judge has deemed admissible, and then deciding what the “truth” of the matter is. This responsibility is multifaceted and requires jurors to engage in several critical intellectual activities.

Firstly, the jury holds the exclusive authority to evaluate the credibility of witnesses. In any trial, you will invariably have witnesses whose accounts may differ, or whose demeanor might suggest something about their truthfulness. It is the jurors, observing the witnesses firsthand—their tone of voice, their body language, their consistency or lack thereof—who must decide whom to believe and how much weight to assign to any particular piece of testimony. Appellate courts are exceptionally deferential to these credibility determinations because the jury is in the unique position of having directly observed the presentation of evidence.

Secondly, and relatedly, the jury is charged with the task of weighing conflicting evidence. Trials are, by their nature, adversarial. One side presents a narrative, and the other often presents a competing one. Evidence may point in different directions. It is the jury’s job to consider all the admitted evidence, to reconcile discrepancies where possible, and ultimately to decide which version of events, or which pieces of evidence, are more persuasive. They must determine the historical facts of the case.

Thirdly, jurors are not limited to considering only direct evidence—that which, if believed, directly proves a fact (like an eyewitness saying they saw the defendant commit the crime). They are also empowered to draw reasonable inferences from circumstantial evidence—that is, evidence of facts from which other facts may logically and reasonably be inferred. For instance, if a defendant’s fingerprints are found at a crime scene, that is circumstantial evidence from which the jury might infer the defendant was present. The law permits, and indeed expects, jurors to use their collective common sense and life experiences to make these logical leaps, provided they are grounded in the evidence presented.

Finally, after wrestling with the evidence, assessing credibility, and drawing reasonable inferences to establish what they believe to be the facts, the jury must then apply the legal standards, as articulated by the judge in the jury instructions, to those facts to reach a verdict. For example, in a criminal trial, they must determine if the prosecution has proven each element of the charged offense beyond a reasonable doubt. In a civil context, the standard is typically a preponderance of the evidence. This application of law to fact is the culmination of their fact-finding journey. This authority over factual elements of a crime is constitutionally protected, and judges cannot usurp this role by making factual findings that would increase penalties beyond statutory maximums without jury determination.

The Aspiration of Impartiality and the Strength of Collective Wisdom

The entire edifice of the jury as fact-finder rests upon the ideal of an impartial jury. This is a cornerstone of our justice system, enshrined in the Sixth Amendment for criminal cases. The theory is that a group of citizens, drawn from a cross-section of the community, can approach the evidence without preconceived biases or prejudices, ready to render a decision based solely on what is presented in court and the legal instructions provided by the judge. This ideal strives to ensure that verdicts are not tainted by favoritism, animosity, or any external considerations.

Beyond mere impartiality, the jury system is also lauded for its potential to promote accuracy through collective deliberation and diverse perspectives. The thinking here is that when individuals from various backgrounds, with different life experiences and viewpoints, come together to analyze evidence, they are more likely to arrive at a well-reasoned and accurate conclusion than a single decision-maker, such as a judge, might. Different jurors may recall different pieces of evidence more vividly, or interpret nuances in testimony in varied ways. Through discussion and debate in the jury room (the specific dynamics of which are deferred to trial practice chapters), these diverse perspectives can challenge individual assumptions, uncover potential biases, and lead to a more thorough and robust examination of the facts. This collaborative process is believed to act as a safeguard against individual error and to foster a more holistic understanding of the case.

The Jury’s Function Within the Adversarial Framework and its Relationship to Evidentiary Rulings

Our legal system is predominantly adversarial. This means that two opposing sides—the prosecution and the defense in a criminal case, or the plaintiff and the defendant in a civil case—present their respective cases before a neutral decision-maker. In a jury trial, that neutral decision-maker, with respect to the facts, is the jury. However, it is absolutely critical to understand that the jury does not operate in a vacuum, nor does it get to hear every piece of information that might theoretically be relevant to a case.

This is where the judge’s role as the “gatekeeper” of evidence becomes paramount. The judge, by ruling on evidentiary objections and motions, determines what evidence is admissible and, therefore, what evidence the jury will be permitted to see and hear. The jury only considers the evidence that successfully passes through this judicial filter. If evidence is deemed inadmissible—perhaps because it is irrelevant, unduly prejudicial, hearsay without an applicable exception, or obtained in violation of constitutional rights—the jury will typically be shielded from it entirely. Thus, the factual landscape upon which the jury deliberates is carefully curated by the judge’s application of the rules of evidence. While the jury reigns supreme in finding facts from the admitted evidence, the scope of that evidence is strictly controlled by judicial rulings on admissibility.

The Fundamental Divide: Questions of Law for the Judge, Questions of Fact for the Jury

A foundational principle underpinning the entire trial structure is the division of labor between the judge and the jury: the judge decides questions of law, and the jury decides questions of fact. This distinction, while generally clear, is the bedrock of their respective roles. Questions of law include, for example, the interpretation of statutes, the content of legal doctrines, the rules of evidence themselves, and the formulation of the legal instructions that will guide the jury. These are matters for which legal training and expertise are essential, and they fall squarely within the judge’s province.

Conversely, questions of fact concern what actually happened: who did what, when, where, why, and with what intent or knowledge. These are the historical events and the human actions and motivations that are in dispute. As we’ve discussed, resolving these factual disputes is the exclusive domain of the jury. The judge instructs the jury on the applicable legal principles, and the jury then applies those principles to the facts as they have found them to be.

However, the line between questions of law and questions of fact can occasionally become blurry. There are instances of what legal scholars term “mixed questions of law and fact.” These occur when a legal standard must be applied to a specific set of determined facts, and the application itself seems to involve both factual judgment and legal interpretation. For example, determining whether a party acted “reasonably” under certain circumstances requires the jury to make a factual assessment of what occurred and then to apply a legal standard of reasonableness. Similarly, while judges typically determine the admissibility of evidence, this can involve preliminary factual findings – for instance, whether a statement qualifies under a particular hearsay exception might depend on a factual determination about the declarant’s state of mind. Judges may also take “judicial notice” of facts that are indisputably true, though in criminal cases, the jury is not necessarily bound to accept such noticed facts as conclusive. Despite these nuanced areas, the core principle remains: the judge commands the law, and the jury commands the facts. Even when judges make rulings on the relevance or probative value of evidence, they must be careful not to invade the jury’s province by pre-judging the weight or credibility the jury might assign to that evidence.

Guiding the Trier of Fact: The Role of Limiting Instructions

In the course of a trial, it is not uncommon for a piece of evidence to be legitimately admissible for one purpose but inadmissible, or potentially prejudicial, if considered for another. For instance, evidence of a defendant’s prior conviction might be admissible to impeach their credibility if they choose to testify, but it is generally not admissible to prove they have a propensity to commit crimes and therefore likely committed the crime currently charged. Similarly, an out-of-court statement might be offered not for the truth of what it asserts, but to show its effect on the listener.

In such situations, the judge will provide the jury with a limiting instruction. This is a specific directive from the court explaining that the evidence they are about to hear, or have just heard, may only be used for a particular, enumerated purpose and not for any other. For example, the judge might instruct: “Ladies and gentlemen, the evidence you are about to hear concerning Defendant X’s prior conviction for perjury is admitted solely for the purpose of helping you assess Defendant X’s credibility as a witness. You may not consider this evidence as proof that Defendant X committed the crime charged in this case or has a tendency to commit crimes.”

The theory behind limiting instructions is that jurors can and will follow the judge’s directives, effectively compartmentalizing the evidence and using it only in the legally permissible way. These instructions are a vital tool for ensuring that evidence serves its proper function within the trial, allowing relevant information to be presented while attempting to mitigate the risk of unfair prejudice or misuse by the jury. While legal scholars and practitioners sometimes debate the practical effectiveness of jurors being able to fully disregard the improper implications of certain evidence, limiting instructions remain a cornerstone of how our system attempts to manage the flow of information to the fact-finder and guide their deliberations.

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