How To Prove a Witness Is Lying?

As an attorney, it is up to you to do everything you can to solidify your case, and in some cases, figuratively, that means proving a witness is lying. But how can you tell and what is the best way to expose a liar in court?

As an attorney, being able to determine if someone is lying in court can provide you with the circumstances you need to overturn a conviction or have charges dropped for a crime on behalf of your client. Instead, what tends to happen is that the exposure of the lie and the intended goals behind lying give you, the attorney, the leverage you need to request that the charges be dropped or that the intended consequences be reduced for your client.

If you can determine that a witness is lying and you can get them to explain why they lied about the incident, it will give your case a great amount of ammunition.

During a trial, the purpose of your cross-examination is to get testimony from any witnesses that will strengthen your side of the case and to challenge any weaknesses. If you are able to prove there was a lie, especially if that lie relates to a central fact that is currently being disputed, you can discredit the witness by proving the witness lied and continuing with your line of questioning until such time as you get to the reasoning behind why the witness lied. You might also consider presenting an affidavit — a written statement confirmed by oath or affirmation of the witness — and present it in the court to reveal inconsistencies in the witness's testimonies.

Why does the ‘why’ matter?

Because the only thing you do is submit a line of questioning that attacks the witness, it doesn’t necessarily expose the thought process behind the lie, what motivations the witness had, and what they were trying to achieve by lying.

For example, imagine a government-employee driver hit a pedestrian who was legally in the crosswalk while the driver was making a left turn. After leaving the accident, the driver took the truck back to the government depot and filled out the official accident report. Even though he knew that he had never seen the pedestrian in the crosswalk before he hit the pedestrian, he wrote something else in the report stating that the pedestrian ran out from between two parked vehicles, tripped over the sidewalk, and fell under the tire. However, this driver did not realize that a traffic camera at the intersection recorded the entire thing.

In this example, as the attorney, you could prove the lie by asking if the driver knew there was a video camera. When the driver says they did not, you can state that they lied in the accident report and ask them if this is correct. This is a very fast way to get to the truth and prove a witness is lying, but it doesn’t make the most out of the potential impact on the case.

Instead, a more comprehensive line of questioning will help you to develop why the driver created that lie, what choices they made when they decided what they were going to lie about, and what they wanted to achieve by telling the lie. This will not only prove a witness is lying but serve as a way to compel the judge or jury and win the argument.

The use of a legal citation maker while preparing before the court can empower you with the needed laws and codes for use in building the case or citing as part of in-court documentation. You need to ensure everything is prepared thoroughly before the court proceeding, and using the citation maker is what can help you stay assured the information is from trusted and reliable sources.

As a lawyer, the way for you to prove a witness is lying, and to get to the truth in court, you need to go about the witness’s testimony and the criminal proceedings a little differently.

If you consider the example above of the trucker and the accident, you should carefully incorporate certain words into your line of questioning, such as:

These are words that you want to deliberately and patiently incorporate throughout the course of your questioning to prove someone is lying. 

These are the first steps, a line of questioning that establishes the education received from the company as it pertains to filling out an accident report. This lays the foundation.

Thereafter, you can focus on the thought process behind telling the lie. Comparing or contrasting different choices can be a great way to get a witness to explore the reason why they told a lie.

After that, you want to focus on things like the motives for this dishonesty and the willingness of the witness to lie.

For example, you can ask them if they were concerned about losing their job or being disciplined as a result of the accident and whether they chose to put fraudulent information in the report.

As an attorney, you can leave the witness to even more areas of questioning, during which time the judge or jury is given the opportunity to come to their own conclusions, to see that the witness is a liar, and to recognize why the witness lied. Your job isn’t to outright call them a liar in court or on the record but instead to focus on their conduct, their actions, and their choices. Being able to successfully probe through the lie and explore the motivations and the decisions that went into that will discredit the witness and the adversary.

If a witness lies in court, they can be convicted of perjury. Most of the time, this is not going to happen, but the judge does have the authority to put them in jail for a short time frame as a result of breaking the law.

As an attorney working a criminal defense case or any other criminal case, any statement or evidence provided by an expert witness or any other type of person can make the difference between a conviction on multiple charges and winning your case. The best legal advice for attorneys is to be patient and deliberate while trying to expose a witness for lying.