The second and even more important lesson is that if you mistakenly include an opinion in your report, admit it - sincerely and non-defensively.
Q: You didn't ask Mrs. Baxter if she was in fact nervous, did you? A: [Thoughtful pause, looks at Mrs. Baxter then back at the questioner and sincerely responds.] No, I didn't. I should have. And I could've asked if I was doing anything to make her more nervous than a stop usually does because I certainly didn't intend to. Q: [Stunned, flat-footed, defense attorney recovers.] So your statement Mrs. Baxter appeared nervous was just your opinion, wasn't it? A: [Again thoughtful.] I guess you're right. I didn't think of it like that at the time but I should've just stuck to what I observed that made me think Mrs. Baxter was more nervous than most folks during a routine traffic stop. Q: [Defense attorney is now shooting blanks.] That's right officer, you should have! A: Yes ma'am, I should have.
This cross examination, like many, has nothing to do with the evidence. Its purpose is to make the officer feel defensive. If the officer allows that, he will act defensive. What kind of people act defensive? Guilty people. That's what the jury will see. Don't let yourself be put on trial. When someone looks us in the eye and sincerely says, "I made a mistake," our reaction is they're honest, we can trust them to level with us. That message to a jury will have you win your credibility confrontation every time.