Drama in the Courtroom! When and How to Impeach a Mock Trial Witness


Impeaching a witness means discrediting them by suggesting that they are confused, mistaken, or outright lying. Because you’re calling the witness out, impeachment is about as dramatic as it gets in a mock trial courtroom. And it’s a witness’s worst nightmare.

In mock trial, you can impeach a witness when they give trial testimony that’s inconsistent with their witness statement in the case packet. For example, their witness statement says that they didn’t see the crime at all, but when they testify at trial, they say something like “I saw the defendant do it!” 

When to Impeach:

First of all, you only impeach your opponent’s witness. Impeachment is part of cross-examination. 

Impeach the witness if:

  1. If witness’s testimony contradicts with what they said in their witness statement; OR
  2. If witness gives an unequivocal response in the witness statement but tries to equivocate on the stand; OR
  3. If witness’s testimony is an overstatement or understatement 


The difference between the witness statement and the testimony provided in court actually matters. 

Let’s talk about all of this in a bit more detail.

Testimony Contradicts Witness Statement

This is pretty straightforward, and you’ll recognize it when it happens. For example, in the case packet, the witness says, “I saw the defendant wearing a blue shirt on the evening of the crime.” 

But, when the witness testifies at trial, they say, “I didn’t see the defendant on the evening of the crime.” Or they say, “I saw the defendant wearing a red shirt on the evening of the crime.” In either situation, the witness has given testimony that contradicts their witness statement. Think about impeaching if you see this happen.

Testimony is Equivocal, but the Witness Statement is Unequivocal

This is when a witness subtly lies on the stand. Let’s use the same example above, where in the case packet, the witness says “I saw the defendant wearing a blue shirt on the evening of the crime.” 

The witness then testifies at trial, saying “I saw the defendant on the evening of the crime; he might have been wearing a blue shirt.”

There’s a slight difference between the defendant wearing a blue shirt (as the witness said in the case packet) and the defendant possibly wearing a blue shirt (as the witness suggested during the trial).

Consider impeaching the witness if you see something like this during your trial.

Witness’s Testimony is an Overstatement or Understatement

This is another type of a subtle lie on the stand. Let’s switch up the example a bit – suppose you have a witness, who in their witness statement says, “I saw the defendant running toward the park on the evening of the crime.” 

Then, at trial, the witness says, “I saw the defendant walking toward the park on the evening of the crime.” That’s an understatement – there’s a difference between the defendant walking and running toward the park. 

Another example is a witness who says in their witness statement, “I saw people gathering at the park”, but testifies at trial, “I saw a crowd of people at the park.” That’s an overstatement – there’s a difference between an unspecified number of “people gathering” and “a crowd.” 

Listen for testimony that subtly changes the degree of speed, size, shade, etc., of whatever is being described. You should consider impeaching a witness who gives this kind of testimony.

Impeach Only If the Inconsistency Matters

Don’t impeach every witness for every minor inconsistency. Impeach only if the inconsistency makes a difference for your case. For example, if another witness saw the crime take place and they say that the person who committed the crime was wearing a blue shirt, then the color of the defendant’s shirt matters. So, if the witness you’re cross-examining says in their witness statement that the defendant was wearing a blue shirt, and then at trial they say that the defendant was wearing red or “might have been” wearing blue, you need to impeach the witness.

But if there were no eyewitnesses to the crime, and no one can testify about what the person committing the crime wore, then the defendant’s shirt color doesn’t matter and you don’t need to impeach a witness who gets it wrong.  

Impeach only if the testimony hurts your case. If testimony doesn’t hurt your case, it doesn’t matter. For example, suppose the crime took place at the park, but it’s unclear who committed the crime. And suppose that in their witness statement, a prosecution witness says there were people gathered at the park. If that witness testifies at trial that a “crowd” of people were at the park, that could help the defense, because the testimony suggests that there is a large number of people who could have committed the crime, making it less likely that the defendant did it. In this scenario, the defense might choose not to impeach the prosecution witness. 

How to Impeach

There are three steps to impeaching a witness:

  1. Repeat the witness’s testimony and ask them to confirm. 
  2. Ask the witness to confirm that they previously gave an honest and accurate witness statement.
  3. Read from the witness statement, citing the page and line number. 

Step 1: Confirm the Witness’s Testimony

The goal here is to “lock in” the witness’s testimony. 

You can do this by paraphrasing or summarizing what the witness just said on the stand. Make sure that the way you paraphrase or summarize the testimony shows that it is inconsistent with what’s in the witness statement.

After you paraphrase or summarize the testimony they just gave, ask the witness if you got it right or if that accurately states their testimony.

Step 2: Confirm That the Witness Previously Gave an Honest and Accurate Witness Statement Before Trial

Next, ask the witness if they provided a statement before the trial. Ask if they were honest and as accurate as possible when they gave their statement. They’ll have to answer “yes” to both questions. If the case packet tells you when and to whom the witness statement was provided, have the witness confirm those facts too.

Step 3: Read From the Witness Statement in the Case Packet

First, announce that you are going to read from the statement previously provided by the witness. Cite the page and line numbers you will be reading. Then, carefully read the portion of the statement that is inconsistent with the testimony the witness just gave. Take your time doing this, and be sure to emphasize important words and phrases. As you read the statement, it should be clear to anyone who’s listening that the witness said something different in court.

Don’t Give the Witness a Chance to Explain the Inconsistency!

After you read from the witness statement, pause briefly, then move on to the next question in your cross-examination. 

Do not point out that the witness statement is inconsistent with the testimony given in court. Do not ask the witness why they answered differently in court. Do not give them a chance to explain themselves! Just move on.

Impeachment Sample 

Q: You saw the defendant wearing a red shirt on the evening of the crime, is that right? [Step 1.]

A: Yes.

Q: Do you recall giving a witness statement in this case? [Step 2

A: Yes.

Q: You gave that statement to Officer Smith, the same day Victor’s home was burglarized, didn’t you? [Step 2.]

A: Yes.

Q: You were being truthful and honest when you gave that statement to Officer Smith, weren’t you?  [Step 2

A: Yes.

Q: I’d like to direct the court’s attention to page 18, lines 5-6 of the case packet. “I saw the defendant wearing a blue shirt on the evening of the crime.” [Step 3.]



When done correctly, impeaching a witness creates some drama and excitement that captures your audience’s attention. And when done properly and confidently, impeaching a witness makes you look like a total pro. Best of all, it discredits your opponent’s witness and weakens their case.

But because witnesses are usually pretty well-prepared, there aren’t too many opportunities to practice this skill. To help you make the most out of any opportunity to impeach a witness, I’ve created a step-by-step guide that you can print out and put in your trial binder for reference.

You can download it here: Printable: Impeaching a Witness

Good luck and have fun with it!