Can a witness be ignorant about a question asked to him in court?

Question

Is it acceptable for a witness to give an answer to a question posed to them in court as I dont know or I'm uncertain?

This is not a refusal to testify; it's just a lack of knowledge. Does the justice system allow for the option that a witness simply does not know the answer to a question?

Maybe it served no real purpose for parties to inquire about a topic that a witness is uncertain about.

What could happen if a witness is asked about the shoes a robber was wearing? The witness says "I looked the robber in the eyes, but I didn't notice his shoes", and his credibility as witness is now being questioned because how could you not look at the shoes?

Answer 1

In addition to David's answer - it's more than acceptable for a witness to say that they don't know the answer; it's a requirement of their oath / affirmation to say "I don't know" if they are telling:

...the truth, the whole truth, and nothingbut the truth..

Answer 2

Yes

"I don't know" answers are quite common in trials, and are perfectly acceptable. Indeed in some cases the aim of a question, particularly on cross examination, may be to get a witness to admit that s/he does not know something that it was earlier implied that the witness did know.

An ideal witness will not claim to know something that s/he does not in fact know, although many witnesses feel that they must give a definite answer, even when they lack definite knowledge. A judge may instruct the witness to make a definite answer only if the witness is certain.

Answer 3

Banning 'I don't know' would be contrary to witnesses needing to be truthful

Let's propose the following question asked by an attorney (and it would have a good reason to be asked, with the answer being material to the case):

"Witness, what is in this box?"

The witness could know it and then would need to answer with that information. But the witness could also not know it, and then would be required to tell so — because they are not allowed to guess. So, our witnesses might answer truthfully with any sentence that transfers that information that they don't know. Be it "I don't know", or a more elaborate way like "Whatever you have put into the box, Mr. Attorney. I can't know what you have put into the box there" would also be allowable.

However, if witnesses would be banned from saying that they didn't know something, it would force them to invent stuff that is not truthful — and thus directly contradictory to the duties of a witness! This is especially true in that a witness may only not answer a question if they would make themselves (or in some jurisdictions also close relatives) the suspect of a crime.

Answer 4

Part 1 Title 7 Chapter 5 Section 125 of the California Penal Code states:

An unqualified statement of that which one does not know to be true is equivalent to a statement of that which one knows to be false.

When one makes an unqualified statement of X, one is implicitly stating that one knows that X is true. Thus, if you don't know that X is true, such a statement is perjury. Ultimately, a witness' testimony is not of what is true, but what they have personal knowledge of (or, in the case of an expert witness, what opinion they have, informed by their personal knowledge of the events of the case and their professional expertise). If you don't have personal knowledge of a fact, then it is inappropriate to give unqualified testimony to that fact. If not misleading the trier of fact as to one's level of knowledge causes the trier of fact to give less credence to one's testimony, so be it. Intentionally giving misleading testimony to make oneself seems more credible is perjury.

If a party doesn't have a reasonable expectation that the witness would have personal knowledge of the matter, then it's inappropriate for them to ask the question in the first place, and the other party can object to the question (e.g. "Objection: calls for speculation"). For instance, if a cop comes in after the robber was subdued by a security guard, and after the security guard has taken the robber's gun away, and a lawyer asks the cop "What hand was the robber using to hold the gun?", that would be improper, as there would be no way for them to answer that without engaging in speculation or hearsay.

Answer 5

There would be many situations where it is impossible for the witness to know the answer, such as conversations in a foreign language, or over the phone, or details not visible to the witness.

You can also have situations where the witness cannot understand the question, such as when jargon is being used. Alternatively, the question might involve a matter of judgement or opinion, though that is usually objected to.

Even Expert witnesses will say they don’t know, though they’re more likely to express it as not being qualified to answer.

So yes, of course it’s OK to plead ignorance.

Of course, if the answer is “I don’t know” too often, you might question why the witness was called at all. That’s often the intention in cross examination, of course.