Most lawyers will tell you that your case is won or lost in jury selection. Then again, most lawyers tell you the same thing about an opening statement. And again about proper preparation. There's plenty of advice out there. While I don't think a case is won in any one phase, I do agree it can be lost in any of them.
This is about a criminal case. Jury selection is much different and more informal in a civil case.
First, about 75 prospective jurors are brought into the courtroom. The judge then goes through some preliminary questions with all of them that will allow the judge to screen out a number of people after the jurors tell the judge about their pending vacations, family illnesses, work problems, or any other reason they do not want to serve.
Once those jurors are whittled down to about 40, the court clerk puts the remaining jurors in a bingo ball system. The metal ball is spun (seriously) and the first jurors picked are placed in the jury box. The number of jurors chosen for questioning depends on the courtroom and how many chairs there are.
The judge then goes through her general background questions with each individual juror called into the jury box in front of the attorneys and the defendant. Once that is done, the prosecutor (me) is allowed to ask questions to the jurors. The questions are usually based on the law of the case or whether a juror has some preconceived prejudice towards a certain subject that will come up in the case (gun control, the harshness of drug laws, DWI laws, etc.).
The defense attorney then will question the panel about whether they will hold the prosecution to their burden and view their client as innocent until proven guilty. The judge generally puts a time limit on the questioning for each side. I agree with the limits in most cases as some lawyers, including me, can be a little long-winded.
Then the attorneys, the judge, the clerk, and the defendant congregate and discuss the potential jurors. The prosecutor goes first and puts forth their challenges for cause. This means the prosecutor is asking to dismiss a particular juror because the law says they are not qualified for this case under the law based on their responses. The defense then argues their challenges for cause. These types of challenges are unlimited.
The prosecutor then uses peremptory challenges. This is where the prosecutor can get rid of a juror for any non-discriminatory related reason. The defense attorney then uses theirs. There are only a certain number of these challenges which varies depending on the type of case (there are 20 for each side in a murder case for example).
The jurors left are selected as the jurors for the case. The clerk then picks more names out of the bingo ball for the next panel from the jurors left in the audience. The process repeats until there are 12 jurors and at least 1 alternate chosen. If they need more, they call up another panel and start over.
Jury selection is my favorite part of the trial because it is the only time you get to interact with the jurors. After they are selected, there is no more talking to them. A lot of attorneys are terrified of it because you have no idea what the juror's responses will be. While it can be scary when faced with a question or comment you were not expecting, it's also fun because you really get to see how good you are thinking on your feet and interacting with the general public.