When a jury trial is about to begin, the trial court judge requests a panel of prospective jurors to be sent to the courtroom from the jury assembly room so that the jury selection process can begin. After reporting to a courtroom, the prospective jurors are first required to swear that they will truthfully answer all questions asked about their qualifications to serve as jurors in the case.

The perjury admonishment, which basically requires potential jurors to tell the truth when answering the questions, is read as follows:

"Do you, and each of you, understand and agree that you will accurately and truthfully answer, under penalty of perjury, all questions propounded to you concerning your qualifications and competency to serve as a trial juror in the matter pending before this court, and that failure to do so may subject you to criminal prosecution?"

The court clerk calls groups of jurors for questioning by the judge and the attorneys. The judge speaks to the jurors, telling them the names of the people involved in the case and stating what the case is about. The judge and the attorneys ask jurors questions to determine if the jurors are free of bias (prejudice) or whether there is any other reason why they cannot be fair and impartial; this process is called voir dire.

It is important to ask questions if you do not understand a question. Each juror is obligated to follow the law as explained by the judge; if you can not follow the law, you must let the judge know.

The law lets the judge and the lawyers excuse individual jurors from service for various reasons. If a lawyer wants to have a juror excused, he or she must use a "challenge" to excuse the juror. Challenges can be for cause or peremptory. There are unlimited challenges for cause, as well as 10 peremptory challenges in criminal cases (20 in death penalty or life imprisonment cases) and 6 in civil cases (Cal. CCP § sec. 231) per side.

The process of questioning and excusing jurors continues until 12 persons are accepted as jurors for the trial. Alternate jurors may also be selected. The judge and attorneys agree that these jurors are qualified to decide impartially and intelligently the factual issues in the case. When the selection of the jury is completed, the jurors take the following oath:

"Do you, and each of you, understand and agree that you will well and truly try the cause now pending before this court, and a true verdict render according only to the evidence presented to you and to the instructions of the court?"

As a juror you should think seriously about the oath before taking it. The oath means you give your word to reach your verdict upon only the evidence presented in the trial and the court's instructions about the law. You cannot consider any other evidence and instruction other than those given by the court in the case before you. Remember that your role as a juror is as important as the judge's in making sure that justice is done.

Jurors' duties during the trial
Do not talk to others about the case. This responsibility requires that you not talk at all with the lawyers, witnesses, or anyone else connected with the case. The lawyers understand this rule. You will find that, even at the risk of seeming rude or unfriendly, the lawyers must avoid even casual conversation with you. In order to prevent even the appearance of improper conversation, a wise policy for you to follow is to avoid any contact with the lawyers or the parties. You also cannot talk to anybody about the case. There are important reasons for this: all cases must be decided only on the evidence presented in the courtroom. If you were to discuss the facts of the case or your impressions of it with your family, friends, or with any other person, you might hear their ideas and might be influenced by people who do not know all the facts. If you believe that someone has tried to speak to you about the case, you must report what happened to the judge by contacting the bailiff immediately.

Do not make up your mind before hearing all the evidence. It is also your duty not to form or express an opinion about the case to anyone. This means that you keep an open mind until you have heard the evidence from all sides and the case is given to the jury for deliberation. Only then may you discuss it with your fellow jurors and even then only when all jurors are present.

Do not conduct your own investigation of the case. It would also be a violation of your duty as a juror to conduct any investigation of the case. As a juror you must not become an amateur detective. For example, you must not visit the scene of an accident, an alleged crime, or any event or transaction involved in the case. You should not conduct experiments or consult any other person or reference works for additional information. If the judge feels that an inspection of a place is necessary or will be helpful, he or she will arrange and supervise an inspection by the whole jury. If you have a question about the evidence, let the judge know by handing a note to the bailiff and he or she will make a decision about your question.

Attorneys' opening statements
As the trial begins, the lawyer for the plaintiff in a civil case or the prosecutor in a criminal case may make an opening statement telling you what they expect the evidence to show. The defendant's lawyer may also choose to give an opening statement after the plaintiff's attorney or prosecutor, telling you what the defense expects the evidence to show. The lawyers' statements are not evidence. Their purpose is to give you the framework of the case, the points of conflict, and the issues of the case that you will need to decide. Be careful that you do not let any of the information presented in the opening statements become evidence in your mind. Remember that the lawyers' statements are only their versions of what happened, not evidence.

Presentation of evidence
Evidence may be presented by the attorneys in the form of a written document or an object (a gun, another weapon, a photograph, an x-ray, or some other physical thing). These are called exhibits. Evidence may also include the testimony of witnesses under oath in the courtroom.

Attorneys' closing statements
After all the evidence has been reviewed in court, lawyers for each side may present their final summary of the case, sometimes referred to as an argument. The lawyers can talk about reasons and make conclusions, but these are not evidence; they are efforts to persuade you. You should listen to these statements carefully and consider them thoughtfully, but you must form your own opinion about the outcome of the case.

Judge's Instructions on the Law
Either before or after the closing arguments by the lawyers, the judge will explain the law that applies to the case to you. This is the judge's instruction to the jury. You have to apply that law to the facts, as you have heard them, in arriving at your verdict. You must consider all of the instructions and give them equal consideration. Keep in mind that you must follow the law as the judge states it to you. If the judge gives you an instruction that seems different from what you read here or another instruction given at another trial, you must accept the instruction given by the judge of the case you are deciding as correct and be guided by the judge's statement only. Be sure to ask questions if you don't understand.

When considering the evidence, an important difference exists between civil and criminal cases in the degree of proof required to sustain an accusation. In a criminal case, the defendant, in order to be convicted, must be proved guilty beyond a reasonable doubt. In a civil case, a party suing another has to prove that charge by a preponderance of the evidence. In every trial, the judge carefully explains the degree of proof required to reach a verdict. You should pay careful attention to the instructions on the degree of proof.

After closing statements by the attorneys and the judge's instructions on the law, the bailiff or court attendant will take you to the jury room for deliberations. Your first duty when entering the jury room is to select a presiding juror. The jury should carefully select a well-qualified presiding juror. Their duty is to see that discussion happens in a free and orderly manner, that the issues you must decide are fully and freely discussed, and that every juror is given an opportunity to participate.

After you enter the jury room for deliberations, the exhibits that you are to consider are given to you. If you are not given written instruction from the judge on the law, you may request them. If you feel you need further instructions or to have certain testimony read back to you, inform the judge through the bailiff or the court attendant. Since these purposes can be accomplished only by returning everyone (including parties and lawyers) to the courtroom, you should not make these requests lightly. The procedure usually takes time, but this delay is understandable if you seriously believe doing so is necessary or helpful to you in reaching a verdict.

Quite often in the jury room the jurors may argue and have a difference of opinion. When this occurs, each juror should try to express his or her opinion and the reasoning supporting it. It would be wrong for a juror to refuse to listen to the arguments and opinions of the others or to deny another juror the right to express an opinion. Remember that jurors are not advocates, but impartial judges of the facts. By carefully considering each juror's opinion and the reasons behind it, it is usually possible for the jurors to reach a verdict. A juror should not hesitate to change his or her mind when there is a good reason. But each juror should maintain their position unless conscientiously persuaded to change that opinion by the other jurors. Following a full and free discussion with fellow jurors, each juror should vote only according to their own honest convictions.

In your efforts to reach a verdict, keep in mind that you should consider only the evidence that was presented in the courtroom. You should not guess or speculate about things not discussed in court, but you can draw reasonable conclusions from the evidence presented.

It is important to take the case you are deciding seriously. After all, if you were a party in the case, it would be important to you, and you would want the jury to give it serious consideration even if the controversy appears less significant to others.

All jurors should deliberate and vote on each issue to be decided in the case. When it is time to count votes, it is the presiding juror's duty to see that this is done properly. In a civil case, the judge will tell you how many jurors must agree in order to reach a verdict. In a criminal case, the unanimous agreement of all 12 jurors is required. If the required number of jurors agree on each issue to be decided, the presiding juror will sign and date the verdict, advise the bailiff or court attendant, and return with the signed verdict and any unsigned verdict forms from prior votes to the courtroom.

If a jury cannot arrive at a verdict within a reasonable time and indicates to the judge that there is no possibility that they can reach a verdict, the judge, in their discretion, may dismiss the jury. This situation is a mistrial, sometimes referred to as a "hung jury," and may mean the case goes to trial again with a new jury.