Anyone accused of a criminal offense has the right to a public trial under the Sixth Amendment to the U.S. Constitution. Defendants can sometimes waive their right to a public trial, but they can't compel a private trial. The general public and media have a First Amendment interest in open court proceedings, though these rights are secondary to the interests of the parties to the case.
U.S. Supreme Court Justice Louis Brandeis summed it up when he said, "Sunlight is the best disinfectant." There are a number of public policy reasons that favor conducting legal proceedings in public:
Ensuring a fair trial. Public trials allow the general public to see that the justice system is functioning properly and treating defendants fairly.
Holding the criminal justice system accountable. The presence of interested spectators is thought to keep the judge, jury, and courtroom staff mindful of their responsibilities and actions. Plus, in jurisdictions where judges are elected, voters can observe the performance of their elected judges up close.
Encouraging witnesses to come forward. Historically, public trials were needed to make proceedings known to potential witnesses.
Discouraging perjury. Witnesses are considered less likely to lie in a public tribunal, in the presence of not only the court, but also members of their community.
Not all cases are covered by the media and not all states allow cameras in the courtroom, so what makes a trial "public" under the law? All the Sixth Amendment requires is that, within reason, members of the public and press have the opportunity to attend the trial and report what they have observed.
Trials must be held in a place where the public can attend, and spectators must be allowed in the courtroom. But the Sixth Amendment doesn't require that trials occur in places easily accessible to the public. For example, in the trial of an inmate charged with attacking a prison guard, proceedings can be held in a courtroom inside the prison.
There must be public notice of court proceedings, but court officials need not advertise them. In most jurisdictions, court notices must be published in the official "legal organ" of the city or county (usually a particular newspaper) at least a week in advance of the hearing.
Not everyone can observe every portion of every trial. Judges generally prohibit anyone who might be called to testify from watching any of the trial proceedings before testifying (also known as sequestering witnesses). Also, judges often exclude the media from parts of trials that include particularly sensitive or difficult testimony.
On occasion, judges go to greater lengths and exclude all non-courtroom personnel from the trial ("close the courtroom"). Usually, judges only close a courtroom when there would otherwise be a substantial risk of danger either to particular people or the public at large. The following are appropriate reasons for closing a courtroom:
Safety. In some cases, such as those involving organized crime and gangs, there may be concerns about the safety of the judge, witnesses, or court staff. Court closure may occur, for example, if a witness is in protective custody or previous witnesses have been intimidated.
Privacy. The identities of victims, witnesses, and sometimes defendants may lead to court closure. In rape cases, for example, laws often protect the victim's identity, so the judge may redact the victim's name and close the courtroom when she testifies. Courtrooms are often closed to protect the identity of undercover police officers or confidential informants. Juvenile court proceedings (unless the child is being tried as an adult) are closed to the public to protect the child from future implications of the case. The juvenile defendant's name is even redacted in court pleadings. Similarly, the identities of witnesses and victims who are children are sometimes protected.
Decency. In cases involving sexual exploitation or pornography, or in other cases where graphic or offensive evidence is necessary, the judge may close the courtroom to lessen the ongoing humiliation of the victims and minimize viewing of the offensive materials. For example, in a prosecution for manufacturing and distributing child pornography, the court is likely to close the courtroom for any testimony that requires discussing the children involved or displaying the pornography itself.
Sensitive information. Certain materials will pose a public threat or lose their inherent value if exposed to the public. In trials involving espionage, leaking classified information, and even theft of trade secrets, judges often close the courtroom.
Although judges have the option of closing the courtroom, the Supreme Court has held that they must always consider alternatives to closure. So, trial judges are unlikely to close the courtroom unless there is a clear showing of possible compromise of the defendant's Sixth Amendment rights or any of the exceptions outlined above are at play. Even then, the courtroom closure must be as minimal as possible—judges should order a completely closed trial only if there is no less restrictive alternative to protect the parties involved (such as excluding the media or closing for a portion of the testimony). Otherwise, the judge risks setting the case up for a possible appeal down the line due to denial of the defendant's Sixth Amendment right to a public trial.