A petit jury hears two broad categories of cases: serious criminal prosecutions, where it decides guilt, and most civil lawsuits for money damages, where it decides liability and the amount owed. The cases heard by a petit jury range from felony charges like assault, burglary, drug trafficking, and fraud to civil disputes over personal injury, medical malpractice, defective products, broken contracts, and property ownership.1United States Courts. Types of Juries What a petit jury does not hear is just as important, because several large areas of law, including family court, probate, small claims, administrative hearings, juvenile delinquency, and military courts-martial, are decided without one.
Criminal Cases That Go to a Petit Jury
The Sixth Amendment guarantees a jury trial in all serious criminal prosecutions. Under the Supreme Court’s “petty offense” doctrine, a charge is serious enough to trigger that right whenever the potential sentence exceeds six months of incarceration.2Cornell Law School. Petty Offense Doctrine and Maximum Sentences Over Six Months That line sweeps in every felony and most significant misdemeanors. Minor infractions like traffic tickets or low-level disorderly conduct charges capped at six months or less generally do not qualify.
The jury’s task is to decide whether the prosecution has proven guilt “beyond a reasonable doubt,” the highest standard in American law. The evidence has to leave jurors firmly convinced of guilt, not just leaning that way. A reasonable alternative explanation means the jury should acquit.
Since the Supreme Court’s 2020 decision in Ramos v. Louisiana, a guilty verdict for any serious crime must be unanimous in both state and federal courts.3Supreme Court of the United States. Ramos v. Louisiana Louisiana and Oregon had previously allowed convictions on 10–2 votes, a practice the Court held unconstitutional.
An acquittal is final. Double jeopardy protections bar the government from retrying the case, regardless of what evidence surfaces later.4Cornell Law School. Reprosecution After Acquittal
Who Decides the Sentence
One common misconception: the jury does not usually decide the punishment. In most criminal cases, the jury’s role ends with the verdict. Sentencing then falls to the judge, who applies sentencing guidelines and weighs factors like criminal history, severity, and mitigating circumstances.
Capital cases are the major exception. In states that allow the death penalty, the jury typically decides whether a defendant is sentenced to death or to life in prison. The Supreme Court held in Ring v. Arizona that the Sixth Amendment requires a jury, not a judge acting alone, to find the aggravating factors that make a death sentence legally permissible.5Justia. Ring v. Arizona, 536 U.S. 584 (2002)
Civil Cases That Go to a Petit Jury
The Seventh Amendment preserves the right to a jury trial in federal civil cases involving “suits at common law.”6Cornell Law School. Seventh Amendment That language traces back to an old distinction in English law between “legal” claims (money damages, which got a jury) and “equitable” claims (court orders like injunctions, which a judge decided alone). Federal courts still follow that framework: a lawsuit essentially asking for money to compensate a loss can be put to a jury.7Constitution Annotated. Identifying Civil Cases Requiring a Jury Trial The Seventh Amendment binds only federal courts, though most states provide a similar jury right through their own constitutions or statutes.
Typical civil jury trials include personal injury lawsuits, medical malpractice claims, product liability disputes, breach of contract cases, and property ownership disagreements. The jury decides two things: whether the defendant is liable, and if so, how much the plaintiff should receive.
The Standard of Proof
The burden in civil cases is much lighter than in criminal ones. A plaintiff only needs to show it is “more likely than not” that the defendant caused the harm. Lawyers call this “preponderance of the evidence.” It tips the scale just past the midpoint, nothing like the near-certainty required for a criminal conviction.
Verdict Rules
In federal civil court, the verdict must be unanimous and returned by at least six jurors, unless both sides agree otherwise.8Cornell Law School. Federal Rules of Civil Procedure Rule 48 – Number of Jurors, Verdict, Polling State courts set their own rules, and a majority allow civil juries to reach a verdict without full agreement. The most common threshold is five-sixths, so a 12-person jury can return a verdict with 10 votes.
Some states also cap what a jury can award for non-economic damages like pain and suffering, particularly in medical malpractice cases. When a cap applies, the judge reduces the award after the fact if it exceeds the statutory limit. Jurors are rarely told about the cap, which means they may set damages at a level the plaintiff will never actually collect.
Cases a Petit Jury Does Not Hear
Several large categories of legal disputes are decided by a judge alone, either because the constitutional right to a jury does not extend to them or because the system is specifically designed without one.
Family Court
Divorce, child custody, adoption, and most other family law matters are resolved by a judge. These cases historically fell under equity jurisdiction rather than common law, so the constitutional jury right does not reach them. A handful of states allow jury trials on narrow family law issues, but judge-only proceedings are the overwhelming norm.
Probate Court
Disputes over wills and estates are typically decided by a judge. The rules shift when someone challenges whether a will is valid. A majority of states provide some mechanism for a jury trial in contested will cases, either as a right that must be asserted in writing or at the judge’s discretion.
Small Claims Court
Small claims courts handle low-dollar disputes without juries. The maximum you can sue for varies widely by state, ranging from $2,500 to $25,000, with $10,000 being a common threshold. The tradeoff for losing the jury is speed and cost: small claims cases move faster and are much cheaper to litigate.
Administrative Hearings
Proceedings before government agencies, including Social Security disability appeals, workers’ compensation claims, and professional licensing disputes, are decided by administrative law judges rather than juries.9Social Security Administration. Hearing Process These hearings are less formal than courtroom trials, though witnesses still testify under oath and the decision rests on the evidence in the record.10Social Security Administration. Code of Federal Regulations 416.1453 – The Decision of an Administrative Law Judge
Juvenile Court
The Supreme Court held in McKeiver v. Pennsylvania (1971) that juveniles accused of delinquent acts have no constitutional right to a jury trial. The Court reasoned that juvenile courts prioritize rehabilitation over punishment, and importing a full jury trial would make those proceedings indistinguishable from adult criminal court. Some states have voluntarily extended jury rights to juveniles in limited circumstances, but the Constitution does not require it.
Military Courts-Martial
Military service members accused of crimes face courts-martial rather than civilian trials. Instead of a randomly selected jury of peers, the case is heard by a panel of military officers chosen by the commanding officer who convened the proceeding. An enlisted defendant can request that at least one-third of the panel be enlisted members, but the composition, size, and voting rules all differ substantially from a civilian petit jury.11Office of the Law Revision Counsel. 10 U.S. Code 825 – Art. 25. Who May Serve on Courts-Martial
How This Is Different From a Grand Jury
Petit juries and grand juries are easy to confuse, and the mix-up often changes what people expect from the process. A petit jury sits during a trial and delivers a final verdict. A grand jury works before any trial begins, reviewing evidence presented by a prosecutor and deciding whether there is enough “probable cause” to formally charge someone through an indictment.1United States Courts. Types of Juries A grand jury never decides guilt or innocence.
The practical differences:
- Petit juries have 6 to 12 members; grand juries have 16 to 23.
- Petit juries hear both criminal and civil cases; grand juries handle only criminal matters.
- Trials before a petit jury are generally open to the public, with only deliberations kept private; grand jury proceedings are entirely secret.
- A petit jury’s verdict ends the factual dispute; a grand jury’s indictment simply sends the case forward to trial, where a petit jury will make the final call.