But MacLeod implies he asked a question during cross that they teach law students not to ask. Presumably because it's kind of a slam-dunk (and he got a slam-dunk response). But I'm curious as to why it's a bad idea to ask.
Usually there are a series of elements that together create a fact. If you ask someone if they perjured themselves, they essentially have three choices to avoid a penalty:
1. Lie
2. Rationalize (it wasn't perjury becuase x, y, z) (and which you are not prepared to counter-argue).
3. Take the fifth and refuse to answer.
Your better off getting there questioning various elements, and then presenting an argument that the signed document was invalid.
1. Did you witness the speeding?
2. Were you able to identify the driver of the car?
3. Please read this document (Plaintiff's exhibit A that states "I witnessed the speeding" and "I identified the driver of the car as x"
4. Is that your signature at the bottom of the document?
5. Are there any other signatures on this document?
Then you argue that since important elements in the document were in fact proven to be false, the document cannot be used as evidence that the defendant violated the law. Since there is no other evidence, the violation conviction must be vacated.
I am curious what he would have done if the officer had answered "no." He never addresses that. Possibly the principle he refers is "never ask a question that will turn into a dead end (nowhere to go in the examination) if the witness answers in the unfavorable way" (i.e. "no").
The question you're not supposed to ask is whatever the last question in your line of questioning would generally be. Or, I suppose: 'is the claim I've been asking you to provide evidence for true?'.
In order to get a 'yes', you need to convince the witness of your claim. And most cross-examinations either involve discrediting the witness, or leading them to provide evidence that helps the side they're not on. So they're rather biased.
If you ask it, and get a yes from the witness -- you almost certainly got enough from the witness for any judge/jury in the world to agree with you. So it doesn't really help.
When you don't get a yes, you're opening the door to the witness providing a different explanation for the things you've established. Which you don't want.
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In this case, Macleod had obtained everything he needed from the police officer to demonstrate that he had committed perjury. He could join the dots later, instead of asking the police officer to do so.
But MacLeod implies he asked a question during cross that they teach law students not to ask. Presumably because it's kind of a slam-dunk (and he got a slam-dunk response). But I'm curious as to why it's a bad idea to ask.