After you have presented your evidence, you have an opportunity to submit proposed "jury instructions" to the judge to be read to the jury. Because most judges are required to—and do—a fairly decent job of doing this for routine cases, we normally recommend that you leave it to the judge. But if the judge is particularly hostile, you may want to take a shot at doing this.
Whole books have been written on how to prepare jury instruction. It's a very specialized skill, not something we can teach you in a couple of pages. But if you're determined, start by going to a law library and, with the help of the librarian, finding the jury instruction books judges most often use in your state. Then page through the instructions that relate to traffic offenses. A judge is required to give a jury instruction at your request, if there is evidence to support it. For example, if you testified you had to speed to the hospital with your wife, who was actually giving birth, the judge is probably required to read the jury instruction on the "necessity defense" (see Chapter 3).
The standard instructions, which the judge can usually be trusted to give, include explaining to jurors how they are to understand the duties of the judge and jury, and how they are expected to consider different types of evidence and how to determine the credibility of witnesses. Finally, and most important, the judge will explain the presumption of innocence. Often the judge will say something like this:
A defendant in a criminal action is presumed to be innocent until the contrary is proved, and in case of a reasonable doubt as to whether his guilt is proven, he is entitled to a verdict of not guilty. This presumption places on the State the burden of proving him guilty beyond a reasonable doubt. Reasonable doubt is defined as follows: It is not a mere possible doubt, because everything relating to human affairs, and depending on moral evidence, is open to some possible or imaginary doubt. It is the state of the case that, after the entire comparison and consideration of the evidence, leaves the minds of the jurors in that condition, such that they cannot say they feel an abiding conviction, to a certainty, of the truth of the charge.