Sometimes lay people are amazed at the evidence and other procedural rules that control jury trials. Also, what passes for common knowledge about the law often is dead wrong. Here are some facts about jury trials and the rules that regulate them that might interest you. These are SIMPLIFIED versions of these legal concepts. (Speak to a lawyer about the rest of the story.)
1. "The victim says she'll drop the charges before trial."
A victim of a crime does not bring criminal charges against another person. The prosecutor brings criminal charges. A prosecutor (often in magistrate's court the police officer is the prosecutor) pays close attention to whether a victim wants a prosecution to go forward to trial, but the victim cannot drop criminal charges. Frequently in domestic violence cases, the prosecutor will still push forward even if the wife doesn't want her husband to be tried.
2. "I have signed, notarized statements from five witnesses that I'm gonna bring to trial."
Don't write a check on using these at trial. Hearsay is roughly defined as a (a) statement made before a witness gets on the witness stand and (b) which is offered for its truth. However, what most people don't know is that documents are hearsay too, unless the documents were written by an adverse party or there is another exception to the hearsay rule. (Almost anything that your party opponent says or writes before trial and which helps your case against him, is not hearsay.) Parties, especially in magistrate's court, often bring notarized statements (a.k.a "affidavits") of witnesses to court only to find that the statements are inadmissible hearsay. Interestingly, Scotland has essentially abolished the hearsay rule, and it is almost an afterthought in many other countries.
3. "He told me that he has insurance and that the insurance company will probably pay my damages. I'm gonna tell that to the jury."
Unless an insurance company is being sued directly, the fact that a party has, or doesn't have, insurance is kept from the jury. In most states, the insurance company is not a party. For example, when a friend is about to sue a buddy, he is sometimes told by his lawyer, "Don't worry. You're not suing your friend - you're suing his insurance company." Wrong. The friend is being sued - the insurance company merely steps in to hire a lawyer and pay the claim.
4. "I'm going to testify that he offered to pay me money to settle."
Juries are barred from hearing that one of the parties offered to settle the case or pay medical bills. The idea behind the rule is that no one will offer to settle unless he is sure that his settlement offer won't be used against him at trial.
5. "I'll be a character witness for you in your personal-injury case."
Generally speaking, a jury will never get to hear this because a party's character is inadmissible in a civil case. She cannot put up witnesses to say that she is a great person. The rule is reversed in a criminal trial though.
Speak to a trial lawyer about these and other trial matters. Evidence law is very complex. The above examples do not give the exceptions to the procedural rules.