The short answer to what not to say in court: don’t lie, don’t guess, don’t repeat what someone else told you, don’t volunteer information nobody asked for, don’t use absolutes like “always” or “never,” don’t mention insurance or settlement talks, don’t reveal what your lawyer or spouse told you in private, and don’t get sarcastic with the judge. Everything below unpacks why each category causes trouble and what to say instead.
Honest people lose cases all the time by saying the wrong thing on the stand. The oath raises the stakes on every word, and opposing counsel is listening for exactly the kinds of phrases that create openings.
Lies and Exaggerations
Lying under oath is perjury. Federal law lets a court fine you, imprison you for up to five years, or both, if you willfully state something you don’t believe to be true about a fact that matters to the case.1Office of the Law Revision Counsel. 18 USC 1621 – Perjury Generally Honest mistakes and faulty memory don’t qualify; the government has to show you deliberately tried to mislead the court. Persuading someone else to lie carries the same five-year maximum under a separate statute called subornation of perjury.2Office of the Law Revision Counsel. 18 USC 1622 – Subornation of Perjury If anyone pressures you to shade your testimony, both of you are exposed.
Outright lies aren’t the only problem. Subtle exaggeration does the same damage more quietly. Stretching “a few times” into “constantly,” or “I saw them near the intersection” into “I saw exactly what happened,” hands opposing counsel a wedge. Once a lawyer shows you stretched one fact, they will argue nothing else you said can be trusted. Describe what you actually saw, in the words that fit it most precisely.
Guesses and Speculation
Testimony has to come from what you personally witnessed. Under the rules, a witness can only testify to matters they have direct knowledge of.3Cornell Law School. Federal Rules of Evidence Rule 602 – Need for Personal Knowledge That makes “I guess,” “I assume,” “probably,” and “maybe” red flags. Each one signals you’ve left what you actually know.
Compare two versions of the same moment. “I saw the driver looking at his phone” is an observation. “I think the driver was probably texting” is a guess about an app on someone else’s screen. A non-expert’s opinion is only admissible when it’s grounded in what the witness personally perceived and helps the jury understand the facts.4Cornell Law School. Federal Rules of Evidence Rule 701 – Opinion Testimony by Lay Witnesses “The car was going fast” works, because speed is something you can perceive. “He must have been drunk” doesn’t, because that’s a medical conclusion you aren’t qualified to draw.
When you don’t know, say so. “I don’t know” is a complete answer, and it’s far safer than filling silence with a guess that opposing counsel will replay later.
What Someone Else Told You
Hearsay is any statement made outside the current proceeding that a party offers to prove the thing stated.5Cornell Law School. Federal Rules of Evidence Rule 801 – Definitions That Apply to This Article; Exclusions from Hearsay As a general matter, it isn’t admissible.6Cornell Law School. Federal Rules of Evidence Rule 802 – The Rule Against Hearsay
In practice, that means you can’t testify to what someone else told you as proof the thing they described was true. “My neighbor told me she saw the defendant leave at midnight” is classic hearsay. You didn’t see the defendant leave. The jury has no way to cross-examine your neighbor through you. Sentences starting with “someone told me,” “I heard that,” or “people were saying” invite immediate objections.
There are exceptions, including statements made in the heat of a startling event, descriptions of something happening in real time, and statements about the speaker’s own physical or emotional state.7Cornell Law School. Federal Rules of Evidence Rule 803 – Exceptions to the Rule Against Hearsay Sorting those out is a job for the lawyers and the judge. Your job is to testify to what you personally saw, heard, or did.
More Than the Question Asked
This is where witnesses do the most damage to themselves. Listen to the question, answer it, then stop. If the attorney asks, “Were you at the intersection on Tuesday?” the answer is yes or no. “Yes, I was there because I left a meeting early after arguing with my boss” gives opposing counsel two new threads to pull.
Volunteering is risky because you can’t predict what will become relevant. A detail that seems harmless to you may connect to something you weren’t thinking about at all. The attorneys have prepared their questions; let them drive. If the question is confusing or has several parts, you’re allowed to ask for it to be rephrased. “Could you repeat that?” or “I’m not sure I understand the question” is far better than guessing what the lawyer meant and wandering through topics you weren’t asked about.
Absolutes and Credibility Traps
Words like “always,” “never,” “every single time,” and “absolutely” sound strong but set a standard a single counterexample breaks. Testify that you “never speed” and let opposing counsel produce a decade-old ticket, and the jury doesn’t just learn about the ticket. They learn you overstate, and they start wondering what else you overstated.
Qualified language leaves room for the reality of imperfect memory. “To the best of my recollection” and “not that I recall” sound more honest because they are.
Phrases like “to be perfectly honest,” “truthfully,” and “I swear to God” cause a different kind of trouble. In a courtroom, they imply that everything you said before this moment might not have been entirely truthful. You already took an oath before you started testifying.8Cornell Law School. Federal Rules of Evidence Rule 603 – Oath or Affirmation to Testify Truthfully Flagging one answer as the honest one makes a jury wonder about the rest.
When You Can’t Remember
Witnesses sometimes feel pressured to produce an answer when their memory is actually blank. That pressure leads to guessing, which leads to inaccurate testimony. “I don’t recall” is legitimate when it’s true, and judges and juries know memory isn’t perfect.
If your memory needs a nudge, there’s a formal process. Your attorney can show you a document, like notes you took at the time, to refresh your recollection, and you then testify from your refreshed memory rather than reading the document aloud.9Cornell Law School. Federal Rules of Evidence Rule 612 – Writing Used to Refresh a Witness’s Memory If that doesn’t help, “I still don’t recall” is the right answer. Making up a detail to sound confident is far worse than admitting a gap, because a fabricated specific that later gets disproven poisons everything else you said.
Insurance and Settlement Negotiations
Two topics are specifically barred by the evidence rules, and witnesses walk into both more often than they should.
First, don’t mention whether anyone involved has liability insurance. Evidence that a person was or wasn’t insured isn’t admissible to show they acted carelessly or wrongfully.10Cornell Law School. Federal Rules of Evidence Rule 411 – Liability Insurance An offhand “well, their insurance company already admitted…” can prompt a mistrial motion. If you know anything about coverage, keep it to yourself unless your attorney tells you otherwise.
Second, don’t reference anything said during settlement negotiations. Compromise offers and the statements made while trying to reach one generally can’t be used to prove fault.11Legal Information Institute. Federal Rules of Evidence Rule 408 – Compromise Offers and Negotiations Those discussions are protected so the parties can negotiate freely.
Privileged Conversations
Some communications are legally protected, and revealing them on the stand can waive the protection for good. The two you’re most likely to encounter are conversations with your lawyer and private conversations with your spouse.
Attorney-client privilege covers confidential communications with your lawyer. Federal courts apply privilege rules based on common law, and in civil cases involving state law claims, the state’s privilege rules govern.12Cornell Law School. Federal Rules of Evidence Rule 501 – Privilege in General Voluntarily revealing part of a privileged conversation can waive the privilege for everything on the same subject.13Cornell Law School. Federal Rules of Evidence Rule 502 – Attorney-Client Privilege and Work Product; Limitations on Waiver If someone asks what your lawyer advised you, don’t answer. Let your attorney object.
Spousal privilege protects private communications made during a marriage. It survives divorce and, in most situations, the death of a spouse. It doesn’t apply if the communication was shared with a third party, if one spouse is suing the other, or if one spouse is charged with a crime against the other or their children. The safe approach is the same: if a question touches a private conversation with your spouse, pause and let your lawyer handle the objection.
Sarcasm, Profanity, and Arguing with the Judge
Federal courts can fine or imprison anyone whose courtroom behavior obstructs the administration of justice.14Office of the Law Revision Counsel. 18 USC 401 – Power of Court Contempt penalties are usually a fine or a short period in jail, but they can escalate for repeated or egregious conduct.
Even behavior that doesn’t reach contempt still hurts. A witness who snaps at opposing counsel or rolls their eyes looks like someone with something to hide. Juries notice composure. Staying calm under aggressive cross-examination signals confidence; losing your temper suggests the attorney struck a nerve. Address the judge as “Your Honor” and refer to other people by their last name. The courtesy keeps the focus on your testimony rather than your attitude.
Invoking the Fifth Amendment
The Fifth Amendment protects you from being forced to testify against yourself in a criminal case, and the right applies to witnesses in both criminal and civil proceedings, not only to defendants.15Congress.gov. Fifth Amendment If answering could realistically expose you to criminal prosecution, you can decline. The risk has to be real, not theoretical.
The mechanics matter. You have to actually claim the privilege. Sitting silently or refusing to answer without explanation isn’t enough, and a court can hold you in contempt for that. State clearly that you are invoking your Fifth Amendment right against self-incrimination. Your lawyer can help with the phrasing, but the claim has to come from you.
One trap deserves special attention. If you voluntarily answer questions on a topic, you may lose the right to invoke the Fifth on follow-up questions about that same topic. Courts have held that a witness can’t testify freely about a subject and then refuse to answer when the details get uncomfortable. If you intend to invoke the privilege on a line of questioning, do it from the first question. Testing the waters and clamming up later can be treated as a waiver for the whole subject.