Definition
Perjury is the crime of knowingly making a false statement about a material matter while under a lawful oath or affirmation. It can occur in court testimony, depositions, affidavits, grand jury proceedings, and documents signed under penalty of perjury. Because it attacks the truth-finding function of the legal system, perjury is treated as a serious offense, typically a felony.
Legal Meaning
The legal system depends on sworn testimony being truthful. When a witness raises a hand and swears to tell the truth, or signs a document under penalty of perjury, the law attaches serious consequences to deliberate lies. Perjury is the crime that enforces this promise, and it exists to protect the integrity of trials, hearings, and official proceedings.
Three ideas define perjury. First, the false statement must be made under a lawful oath or affirmation—a formal promise to be truthful. Second, the person must have made the statement knowing it was false; an honest mistake or a faulty memory is not perjury. Third, the falsehood must concern a material matter, meaning a fact capable of influencing the outcome or course of the proceeding. A trivial or irrelevant lie generally does not qualify.
Perjury is defined by statute, and the elements and penalties vary by state and under federal law. Related offenses include subornation of perjury (procuring someone else to lie under oath), making false statements to government officials, and obstruction of justice. Perjury can arise in many settings beyond the courtroom, including in a deposition or before a grand jury.
Key Points
- Perjury is knowingly making a false statement under a lawful oath or affirmation
- The statement must be material—capable of affecting the outcome of the proceeding
- An honest mistake, faulty memory, or good-faith belief is not perjury
- It can occur in testimony, depositions, affidavits, grand jury proceedings, and sworn documents
- Subornation of perjury is the separate crime of inducing another person to lie under oath
- Perjury is generally a felony with penalties that vary by state and under federal law
- It is closely related to obstruction of justice and making false statements to officials
- A perjury conviction can permanently damage a person's credibility and reputation
Real-World Example
During a civil trial, a witness is asked under oath whether she was present at a meeting where a contract was discussed. She was present, but to help a friend's case she testifies that she was not there at all. Her attendance at the meeting is central to a disputed issue in the case. Because she knowingly gave a false answer, under oath, about a material fact, her testimony may constitute perjury.
By contrast, if she simply could not remember whether the meeting occurred on a Tuesday or a Wednesday—a detail that has no bearing on the outcome—an inaccurate answer would not be perjury. The falsehood was neither knowing nor material.
Elements and Common Settings for Perjury
| Element | What It Requires |
|---|---|
| Lawful oath or affirmation | The statement was made under a formal promise to tell the truth |
| False statement | The statement was untrue when it was made |
| Knowledge of falsity | The person knew the statement was false, not merely mistaken |
| Materiality | The false statement could affect the outcome or course of the proceeding |
| Common settings | Trial testimony, depositions, affidavits, grand jury, sworn filings |
Why Materiality Matters
Materiality is often the most heavily litigated element in a perjury case. A statement is material if it has a natural tendency to influence, or is capable of influencing, the decision or the proceeding in which it is made. Importantly, the false statement does not have to actually change the outcome; it only has to be capable of doing so. This requirement ensures that perjury prosecutions focus on lies that matter, not on trivial inaccuracies or harmless slips of the tongue.
Related Offenses
Several offenses cluster around perjury. Subornation of perjury punishes a person who persuades or procures another to testify falsely. False swearing and making false statements to government agencies cover sworn or official falsehoods that may not meet every element of perjury. Obstruction of justice is broader still, covering conduct that interferes with the administration of justice. Many of these can be charged alongside perjury, and federal and state statutes define each somewhat differently. Witnesses compelled to testify by a subpoena remain under the same obligation to tell the truth.
Related Terms
Facing a Perjury Issue?
Testimony and sworn statements carry real legal risk. Talk to an attorney before you speak under oath.
Explore Criminal DefenseWhen You Need a Lawyer
Perjury accusations are serious and often arise unexpectedly during litigation or investigations. A qualified attorney can:
- Explain how perjury is defined in your jurisdiction and whether the elements are met
- Advise you before you give testimony, sign an affidavit, or appear at a deposition
- Assess whether a statement was material and whether you knew it was false
- Protect your privilege against self-incrimination when truthful answers carry risk
- Defend against perjury, subornation, or obstruction charges
- Negotiate with prosecutors where a charge has already been filed
If you are preparing to testify or have been accused of lying under oath, consult a lawyer promptly. To learn how court proceedings work, see our guide on responding to a court summons.
Frequently Asked Questions
What are the elements of perjury?
Perjury generally requires that a person, while under a lawful oath or affirmation, knowingly made a false statement about a matter that was material to the proceeding. The person must have known the statement was false at the time, and the false statement must concern a material fact, meaning one capable of influencing the outcome. An honest mistake, a faulty memory, or a statement on an immaterial point is generally not perjury.
Does the lie have to be material to be perjury?
Yes. A false statement is only perjury if it concerns a material matter, meaning the statement has the capacity to affect the outcome or the course of the proceeding. A trivial or irrelevant falsehood, even one made under oath, usually does not qualify. Materiality is a central requirement and is frequently the subject of dispute in perjury cases.
Can you commit perjury outside of a courtroom?
Yes. Perjury can occur anywhere a person makes a sworn statement, including depositions, affidavits, grand jury testimony, administrative hearings, and documents signed under penalty of perjury such as certain government filings. The statement does not have to be made in front of a judge. What matters is that it was made under a lawful oath or its equivalent.
What is subornation of perjury?
Subornation of perjury is the separate crime of persuading, inducing, or procuring another person to commit perjury. For example, a person who convinces a witness to lie under oath may be charged with subornation of perjury even if they did not testify falsely themselves. Like perjury, it is a serious offense against the integrity of the legal system.
What penalties does perjury carry?
Perjury is generally a felony and can result in fines and imprisonment, with penalties varying by state and under federal law. Because perjury undermines the truth-finding function of courts, it is treated seriously, and a conviction can also damage a person's credibility and reputation. The specific penalties depend on the jurisdiction and the circumstances of the false statement.