Witnesses are a critical part of criminal trials. Strong testimony from even one good witness can sometimes make or break the prosecution’s case. The three most common types of witnesses are lay, expert, and character witnesses. Each plays an important role in the discovery of truth.
What Is a Witness?
In a criminal trial, witnesses are individuals who provide evidence relevant to the case. A witness might provide evidence that places the defendant at, or far from, the crime scene. Witnesses also provide context that supports or undermines other evidence presented at trial.
All witnesses must be “competent,” which means they must understand the obligation to tell the truth under oath and be able to communicate their knowledge to a jury. Competency issues often come into play when a witness is very young and can’t distinguish between truth and lies.
Competency differs from credibility (trustworthiness). Typically, a judge will determine if a witness is competent to testify. A jury will decide if or how credible a witness’s testimony is.
What Is Witness Testimony?
The information a witness provides at trial is called testimony. This testimony is evidence in the criminal case. A witness might also provide testimony before trial if called to answer questions in a deposition or before a grand jury. All of these types of testimony are given under oath.
Witness testimony is just one type of evidence. Other types of evidence include documents, photographs, videos, phone records, digital files, voice recordings, fingerprints, and DNA test results. Any type of evidence admitted in a case—including witness testimony—must be reliable and relevant to the issues in question.
What Are the Types of Witnesses?
The knowledge a witness brings to a trial determines what type of witness they are.
Lay Witnesses
Lay witnesses (non-experts) testify about what they’ve personally seen, heard, or observed. They cannot (typically) testify about their opinions or what others may have told them. Examples of lay witnesses are crime victims and eyewitnesses to the crime. Their personal knowledge is often crucial to a case.
Expert Witnesses
Expert witnesses give opinions based on their specialized knowledge, skill, experience, training, or education. Expert testimony must help the jury understand issues that are generally beyond the knowledge of the average person, such as how reliable DNA or fingerprint evidence is. Examples of expert witnesses include medical experts, coroners, forensic scientists, accident reconstruction experts, and handwriting experts.
Character Witnesses
Character witnesses have personal knowledge of the defendant, victim, or other people involved in the case, rather than the crime itself. For instance, a defense attorney might call a neighbor, friend, family member, or clergy member to testify as to the defendant’s or the victim’s personality or reputation.
Can a Witness Refuse to Testify?
Witnesses are crucial to our justice system, as they hold information key to determining the truth or falsity of a matter. Because they are so important, defendants are entitled to have the judge issue a subpoena (suh-PEE-nah) ordering witnesses to appear at the trial and testify, even if they don’t want to do so.
What Happens If a Witnesses Ignores a Subpoena?
If a witness receives a subpoena and doesn’t show up to court as directed, the judge can issue a bench warrant that allows a police officer to haul the witness into court.
Unless that witness had a very good reason for not appearing (such as being in a coma), the judge may find the person in contempt of court (which can come with jail time and a fine). The judge can also order the witness to answer questions. If the witness refuses, the judge can hold the witness in jail until they agree to testify.
When a Witness Has a Right Not to Testify
A witness may very well have a right not to testify. For instance, if a witness’s testimony would implicate them of a crime or expose them to criminal prosecution, they may legally refuse to testify by invoking their Fifth Amendment right against self-incrimination. A witness might also raise a privilege that legally allows them not to testify as to certain communications, such as a spousal privilege or doctor-patient privilege.
But the right not to testify on certain matters doesn't permit the witness to ignore a subpoena. The witness needs to assert their privilege or right, and a judge will determine if the privilege applies or not.
What Happens If a Witness Lies Under Oath?
Lying under oath is a big deal—so much so, it’s a crime. Before giving testimony, the witness must swear to tell the truth (the whole truth, and nothing but the truth) under penalty of perjury. All states and federal law make perjury a crime, typically a felony.
To be convicted of perjury, a witness must knowingly make a false statement that’s material to the case. A witness who makes an honest mistake or fails to remember exactly what happened has not committed perjury. These mistakes or failings are relevant to the credibility and weight given to witness testimony but are not crimes.
Do Witnesses Have Lawyers?
A witness may hire a lawyer, and some do. It’s important to know that the prosecutor or defense attorney calling the witness to testify does not represent that witness. The prosecutor and defense attorney represent their clients and have no obligation to protect the witness. For this reason, a witness might want to secure independent legal representation. An attorney can help a witness prepare for their testimony and protect their legal rights.