The vast majority of cases are settled by plea bargaining, which is the reason most cases don't go to trial. Plea bargains have pros and cons for both the defense and the prosecution, and affect how the courts function.
Plea bargaining refers to the negotiations between prosecutors and defense lawyers on how to resolve a criminal case. A plea bargain or plea deal results in the defendant pleading guilty or no contest (also called nolo contendere, which is like a guilty plea). In return, they receive a benefit, such as a lower sentence or a reduced charge.
Plea bargains are a crucial part of the criminal legal system. Criminal courts are crowded with way more cases than can be brought to trial, which means prosecutors and judges need to move cases quickly through the system. Without plea bargains, the criminal courts wouldn't be able to function in a way that protects a defendant's constitutional rights, such as the right to a speedy trial.
That said, while there's a right to a trial and even a right to plead guilty, there's no right to a plea deal. In some circumstances, the prosecutor might have no interest in a plea bargain. For instance, in cases involving very serious charges and a lot of public outcry, the prosecutor might want to avoid giving the defendant a break. They're under no obligation to make a plea offer.
Plea bargaining can take place at various times in the case. In some cases, the prosecutor, or sometimes the defendant, makes a plea offer early. In states that have preliminary hearings on felony charges, for example, the prosecutor might make an offer on the condition that the defendant accepts it before the hearing.
Or, plea bargaining might occur after something significant happens as the case moves forward. For example, if the defendant loses a motion to suppress evidence, they might be more interested in a plea deal than they were before the motion. Of course, at that point, the defendant's bargaining power might be reduced, now that the prosecutor knows the evidence is coming in.
In some cases, plea negotiations can continue up until the day of trial. And in rarer cases, they might continue right up to (or during) jury deliberations; in that situation, the prosecutor might realize that the case didn't turn out to be as strong as anticipated, and might agree to a plea deal to avoid the possibility of an acquittal. But normally, a plea deal is reached well before that point.
Plea bargains offer incentives for both sides, though the benefits might be greater in some cases than in others. The most obvious benefit is that it reduces certain risks for each side.
Defendants who plead under a plea bargain can avoid the risk that:
Plea deals also allow a defendant to avoid the public attention and embarrassment that can come with a trial.
And a plea bargain might allow a defendant to plead to an offense that avoids consequences beyond the criminal case. For example, they might be able to plead to a reduced charge that doesn't result in deportation or the loss of a professional license.
From the prosecutor's point of view, a settled case will clear the trial calendar, leaving room for other cases. It also removes the risk that the defense will convince the jury to acquit or hang.
Settled cases result in happy judges, too, because their caseloads lessen. Prosecutors, who often regularly appear before the same judges, have an interest in maintaining good professional relationships with them. Keeping cases moving along in the judge's courtroom certainly can't hurt.
Defendants and prosecutors have reasons not to plea bargain, and in any given case, they might choose to go to trial instead.
A defendant who pleads guilty must admit guilt. They lose the chance to convince the trier of fact, be it a judge or jury, that they're not guilty. The most seasoned trial attorneys, whether they're prosecutors or defense attorneys, would be hesitant to say that any particular case is a slam dunk for the prosecution. Juries are unpredictable, as are witnesses. But pleading guilty removes the possibility of an acquittal.
Also, the defendant might be afraid that admitting guilt will damage his relationship with family, friends, and community. This concern can be heightened in sensitive cases, such as sexual abuse allegations or other charges involving taboo behavior.
Further, pleading guilty usually means the defendant can't appeal the conviction or sentence they receive.
Prosecutors lose a bit, too, when they bargain a case. Victims and the public may be angered at a settlement for a crime they think should go to trial. And when the deal doesn't include a specified, agreed-upon sentence, the prosecutor could end up unpleasantly surprised when the judge hands down a lenient punishment.
Not every case can be bargained "down." In some instances, when a statute provides for a mandatory minimum sentence, the prosecutor can't agree to a lighter sentence. For example, statutes dealing with driving under the influence of drugs or alcohol often specify that increased penalties apply for repeat offenders; and certain assault crimes carry an enhanced sentence when the victim was a child or other protected person.
In these situations, the prosecutor might be able to reduce the charges (to reckless driving or a lesser assault, for example). But, without reducing the charges, the prosecutor wouldn't be able to promise a lighter sentence than the minimum required for the original charge.
A number of factors affect whether the defendant will get a plea deal. Some involve constitutional issues surrounding plea deals that relate to the role of the judge, the prosecutor, and the defendant.
Under the constitutional principle of "separation of powers," the judge and the prosecutor have distinct roles to play in the plea bargaining process.
One limitation that comes into play is that judges can't plea bargain with defendants when the prosecutor refuses to. Although many jurisdictions allow judges to participate in plea discussions between the parties, it's up to the prosecutor to decide whether the defendant gets a plea deal at all.
But when a prosecutor won't agree to a deal, a judge can announce an "indicated sentence"—a forecast of what the sentence would likely be if the defendant pleads. The court can't suggest that the sentence would be greater if the defendant went to trial; that would violate the rule that judges can't plea bargain with defendants. But a defendant who went to trial would still risk a longer sentence because, at that point, the judge will have heard all the evidence, which might justify greater punishment. So, a defendant without a plea deal might choose to cut their losses and just plead, with the expectation that they'll get the indicated sentence and that they probably won't do any better if they lose at trial.
One area where judges hold all the power is in deciding whether to accept or reject a plea deal. Plea bargaining that attempts to nail down a specific sentence must involve a willing judge for the bargain to be a deal the defendant can rely on. That's because sentencing is entirely the judge's job—no prosecutor can authoritatively tell the judge, "This is what the defense and I have agreed will be the sentence." The parties can inform the court that they've reached a deal, but it's up to the judge to decide whether to honor it.
Sometimes, the bargaining discussions will involve the judge from the outset, and when that happens and the judge signs off on the deal, the sentence is set. And most times, even when judges aren't involved but the parties agree on the sentence, the judge will approve the deal and impose the sentence the parties agreed on. But sometimes the judge will reject the deal for any number of reasons.
And in some cases, the deal will involve only a promise that the prosecutor will not ask for a sentence greater than a certain amount. In these cases, there's no guarantee that the judge will follow this recommendation. To protect themselves in these scenarios, defendants often build into the deal the option to withdraw the plea if the judge indicates that he or she will impose a sentence other than the one recommended by the prosecutor. (For more, see Withdrawing a Guilty Plea.)
Under the U.S. Constitution, a defendant's guilty plea must be "knowing, intelligent, and voluntary." (Boykin v. Alabama, 395 U.S. 238 (1969). So, defendants who plead guilty under a plea deal must not only appear before a judge and admit guilt, they must assure the judge they know what they're doing and are pleading of their own free will.
To make sure the plea is okay under the Constitution, judges will conduct a plea "voir dire" (questioning), asking whether the defendant understands that he or she is giving up certain rights. These include the right to a trial, to testify, and to call and cross-examine witnesses.
The judge will often ask defendants if they understand every element of the offense and if they admit each element, and/or if they've discussed the charges with defense counsel and understand them. The judge will also make sure the defendant understands the terms of the bargain.
Judges won't accept a guilty plea unless a genuine "Yes" follows each of the judge's questions.
Judges conduct these examinations to make sure that defendants are well aware of what they're giving up—and to ensure that later, defendants can't claim they didn't understand their rights when they pleaded guilty.
Because a plea won't happen unless the defendant passes the judge's voir dire, attorneys typically spend some time preparing their clients for this examination. Defendants who resist admitting guilt or conceding the charges, or who waffle on other questions, could have a hard time successfully pleading before a rigorous judge. In some cases, the judge might refuse to take the plea, and the defendant will suddenly be going to trial, even if they don't want to.