The juror oath is the sworn promise that turns a summoned citizen into a legal decision-maker, binding them to try the case fairly, follow the court’s instructions, and reach a verdict based only on the evidence admitted at trial. In federal criminal cases, each juror swears or affirms to “well and truly try, and a true deliverance make in, the case now on trial, and render a true verdict according to the law and the evidence.”1Federal Judicial Center. Oaths Breaking that promise has real consequences: lying during jury selection is perjury punishable by up to five years in federal prison, and misconduct during trial can bring contempt charges or force a mistrial.
The Preliminary Oath During Jury Selection
You actually take two oaths, not one. The first comes at the start of voir dire, before any questioning. Prospective jurors promise to answer all questions truthfully so the judge and attorneys can decide who is capable of being fair.2United States Courts. Juror Selection Process
The questions can feel intrusive. Attorneys ask about your job, your experiences with the legal system, any connection to the parties, lawyers, or witnesses, and anything that might make it hard to keep an open mind. A question that seems personal almost always has a strategic reason behind it.3United States District Court Southern District of New York. The Voir Dire Examination
Honest answers matter here more than people realize. A deliberately false response is not just a selection problem; it is perjury, and courts take it seriously because the fairness of the entire trial depends on jurors having disclosed their actual biases rather than the version of themselves they thought the court wanted to see.3United States District Court Southern District of New York. The Voir Dire Examination
The Trial Juror Oath
After challenges are resolved and the final panel is seated, jurors take the oath that actually creates their legal obligations for the trial itself. The federal criminal version is the “well and truly try” language quoted above. The civil version uses slightly different wording but carries the same commitment: try the issues, follow the law, and base the verdict only on the evidence admitted.1Federal Judicial Center. Oaths
“Well and truly try” does real work. It binds each juror to evaluate the case with the rigor and good faith the system promises to the parties. Federal policy guarantees every litigant a jury drawn from a fair cross-section of the community, and the oath is what activates that guarantee for the individual case.4Office of the Law Revision Counsel. 28 USC 1861 – Declaration of Policy
The Grand Jury Oath
Grand jurors take a different oath because they do a different job. A grand jury does not decide guilt. It decides whether there is enough evidence to charge someone. Grand jurors promise to “diligently inquire into and make true presentment or indictment” of offenses within the district, to keep the proceedings secret, and to act without malice, hatred, fear, or favoritism.1Federal Judicial Center. Oaths
The secrecy obligation is stronger than anything in the trial oath. Grand jurors must “keep your own counsel and that of your fellows and of the United States” and cannot disclose witness testimony or votes except as required in later judicial proceedings. The reason is practical: grand jury investigations often involve uncharged suspects who would be seriously harmed by public disclosure of the evidence against them.1Federal Judicial Center. Oaths
Affirming Instead of Swearing
The standard oath ends with “so help you God,” but you cannot be required to say those words. Article VI of the Constitution prohibits any religious test for public office or public trust, and the First Amendment protects freedom of conscience.5Constitution Annotated. Article VI, Clause 3
Every version of the federal juror oath builds in the alternative. The word “affirm” replaces “swear,” and the religious closing is dropped. The affirmation carries the same legal weight and the same penalties for violation. You do not need to explain your reasons, and the court cannot deny you the option.
What the Oath Requires Once You Take It
The oath is not just ceremonial language. From the moment you take it until the verdict is delivered, you are bound by specific restrictions.
The core duty is impartiality. You must avoid forming opinions about the case until all evidence has been presented and deliberations begin. The Sixth Amendment guarantees every defendant an impartial jury, and courts treat premature judgment as a serious problem because it means the juror has stopped listening.6Legal Information Institute. U.S. Constitution Annotated – Amendment VI – Right to an Impartial Jury: Current Doctrine
You cannot conduct independent research. Federal model jury instructions spell this out plainly: do not use your phone, tablet, computer, or any other device to look up anything about the case, the people involved, the legal issues, or the location of events. If you accidentally come across something relevant in your social media feed, you must ignore it and report it to the court.7United States Courts. Proposed Model Jury Instructions: The Use of Electronic Technology to Learn or Communicate about a Case
You cannot discuss the case outside the jury. Not with family, not with friends, not with coworkers, not online. The federal model instructions name email, text messaging, blogs, and social media as prohibited channels by name. Even during deliberations, when jurors may finally talk about the case with each other, electronic devices stay off-limits for outside communication or research.7United States Courts. Proposed Model Jury Instructions: The Use of Electronic Technology to Learn or Communicate about a Case
And what happens in the jury room stays there. The Supreme Court has long held that private communications with jurors or tampering of any kind threatens the integrity of the verdict and cannot be tolerated.6Legal Information Institute. U.S. Constitution Annotated – Amendment VI – Right to an Impartial Jury: Current Doctrine
Penalties for Breaking the Oath
Consequences depend on what you did and when you did it. Federal law creates several distinct categories, and judges do not treat them lightly.
Ignoring the Summons
If you simply fail to appear after receiving a federal jury summons and cannot show good cause, you face a fine of up to $1,000, up to three days in jail, an order to perform community service, or any combination of the three.8Office of the Law Revision Counsel. 28 USC 1866 – Selection and Summoning of Jury Panels
Lying During Jury Selection
Deliberately giving false answers during voir dire is perjury. Under federal law, anyone who willfully states something material they do not believe to be true while under oath faces a fine and up to five years in prison.9Office of the Law Revision Counsel. 18 USC 1621 – Perjury Generally A separate statute covering false declarations before a court or grand jury carries the same maximum penalty.10Office of the Law Revision Counsel. 18 USC 1623 – False Declarations Before Grand Jury or Court
Five years can sound extreme for a dishonest answer during jury selection, but prosecutions do happen. The usual trigger is a juror who concealed a relationship with a party or a strong bias, and the deception surfaces only after a verdict. At that point, the losing side can seek a new trial and the juror can face criminal charges.
Misconduct During Trial
Running internet searches, contacting witnesses, discussing the case on social media, or otherwise violating the judge’s instructions can result in contempt of court. Federal courts have broad statutory authority to punish contempt by fine, imprisonment, or both for misbehavior that obstructs the administration of justice or disobeys a court order.11Office of the Law Revision Counsel. 18 U.S. Code 401 – Power of Court
Even short of contempt, juror misconduct during trial regularly leads to that juror’s removal and replacement with an alternate. If no alternates are left, the judge may be forced to declare a mistrial, wiping out weeks or months of testimony and forcing the entire case to start over at substantial cost to the parties and the public.