As a layman, can anyone explain why they are taught not to ask this?
The risk is that the witness will flat out deny what they had essentially already admitted to, getting you tangled in rehashing things or else unable to actually prove your point.
More interestingly, the reward is often negative even when that doesn't happen, because it deprives the finder of fact (the judge or jury) of the opportunity to put the pieces together and draw your conclusion with an "aha!" moment and the feeling that the conclusion is their own.
The risk argument makes a lot of sense to me, but this part seems to be putting a lot of faith in the competence of a jury of your peers.
I'd imagine that this "last question" guideline exists because of the experience of trial lawyers, so I'm certainly not saying it's wrong. I was just surprised that that's the way it shakes out. The closing argument thing does make sense, but that seems like it would also deprive the jury of the opportunity to piece it together themselves.
But you don't ask "the last question", which is the one that sums up the point you were trying to make, because then the witness sees how you've shown them to be full of shit, and they'll spend 10 minutes weaseling out of everything you just established. It's SO TEMPTING to ask it directly, because you really want to hit the point home, but it's often too risky because it can backfire by breaking up your flow -- you often have dozens of lines of questioning, and there's a "last question" to each of them.
What you're supposed to do is explain "the last question" in your final submissions, using the transcript from your cross as the proof the statement is true.
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.
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.
He can ask what evidence does the officer have to show that the author was in the car at that point of time when the photo was taken.
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.
And although I'm not a lawyer, my understanding is that probable cause is a relatively low standard to meet, much lower than preponderance of the evidence and certainly much lower than beyond reasonable doubt.
Ask yourself this -- if a witness saw a car (and noted its license plate) parked in a house's driveway during the time when a burglary was likely to have taken place, and the car was unknown to those who lived at that address, would a judge sign a search warrant on that vehicle and the registrant's address based on probable cause?