Opening statement is one of only three times where you can speak directly to the jury, the other two being jury selection and closing argument. Each of the three has its specific function and your preparation and strategy for each will differ accordingly, but there is no question that many cases are won or lost during opening statement. Some cite statistics that 80 percent of all jurors make up their minds during opening statement. It is not debatable that initial impressions made during opening statements, favorable or otherwise, often will form the basis of the ultimate jury verdict.
What you cannot do in opening. In brief: You cannot discuss matters you know cannot be proven, matters of personal knowledge of counsel, matters excluded by motions in limine, privileged matters, the size and wealth of a corporate defendant, settlement offers, subsequent repairs, tax consequences, insurance, or violate the "golden rule" (i.e., asking the jurors to award an amount that they would want to recover if they were in the same position and had suffered the same injuries as the plaintiff). What takes more time and thought is what can you do in opening.
