A few years ago I tried an auto accident case. The defendant driver was 94 years old. By the time of the trial, she was in a nursing home. I never did take her deposition before trial because it was represented to me that she was too ill. Since the accident facts were pretty straightforward (she ran a stop sign), my inability to take her deposition before trial did not concern me.
When the trial started, defense counsel indicated that his client, the elderly driver, would testify at trial. I offered to enter into a stipulation with the lawyer that there was no need to have her testify.
The insurance company refused, apparently thinking that, by putting her on the witness stand, it would create sympathy for the elderly driver.
So the defense attorney put her on the stand. It was a disaster. She was confused, couldn't hear very well, and the questioning didn't serve any real purpose. Despite the disjointed testimony, she did say that she didn't think she saw any cars coming when she entered the intersection.
When it came time for cross examination, the judge asked me if I had any questions.
I stood up and said three words: "No, your Honor." She had done no damage to our case, and the last thing I wanted to do was to ask a single question that appeared to be "beating up" an elderly, confused driver. In my judgment, the jury understood what was going on. And as it turned out, the jury "got it."
Sometimes you need to know when to shut up. In these situations, often the best cross examination is none at all.