A "plea bargain" is a deal offered by a prosecutor as an incentive for a defendant to plead guilty. If every case in the justice system went to trial, the courts would be so overloaded that they would effectively be shut down. Plea bargaining allows the prosecutor to obtain guilty pleas in cases that might otherwise go to trial.
There are two types of plea bargain:
A "charge bargain" occurs when the prosecutor allows a defendant to "plead guilty to a lesser charge," or to only some of the charges that have been filed against him. For example, a defendant charged with burgarly may be offered the opportunity to plead guilty to "attempted burglary." A defendant charged with Drunk Driving and Driving With License Suspended may be offered the opportunity to plead guilty to just the drunk driving charge.
A "sentence bargain" occurs when a defendant is told in advance what his sentence will be if he pleads guilty. This can help a prosecutor obtain a conviction if, for example, a defendant is facing serious charges and is afraid of being hit with the "maximum" sentence. Typically, sentence bargains can only be granted if they are approved by the trial judge. Many jurisdictions severely limit sentence bargaining.
Sentence bargaining sometimes occurs in high profile cases, where the prosecutor does not want to reduce the charges against the defendant, usually for fear of how the newspapers will react. A sentence bargain may allow the prosecutor to obtain a conviction to the most serious charge, while assuring the defendant of an acceptable sentence.
A plea bargain is a contract between the prosecutor and the defendant, and both parties are required to comply with the terms of their contract. If you have a plea bargain with the prosecutor and you are required to perform particular tasks (such as pleading guilty on a particular date, cooperating in the investigation of another offense, or testifying against a co-defendant), the prosecutor may revoke the plea bargain if you fail to satisfy your duties.
If the prosecutor breaks a deal with a defendant, the defendant may seek to have his plea set aside, or may seek a court order requiring the prosecutor to respect the plea bargain. This may happen if the prosecutor has agreed not to authorize additional criminal charges against the defendant in return for the guilty plea, yet subsequently files the charges.
Although most of the time a judge will accept a plea bargain, at times a judge will find that a proposed plea bargain is not in the interest of justice. When that occurs, the prosecutor and defendant can attempt to negotiate a new plea bargain that is acceptable to the judge, or the case may proceed to trial.
Make sure that the plea deal is clearly stated on the record at the time of your plea. Sometimes, the plea deal will be reduced to writing, and will be signed by the parties. It is usually adequate to reference the written plea agreement on the record, without reciting all of the terms. During your sentence, the court will ask you about any promises that you have received, other than the plea bargain stated on the record, in return for your guilty plea. If you answer that there are none, yet the terms of your plea are not on the record, you may find yourself without any recourse if the prosecutor only respects those terms that were stated on the record.
There are rare exceptions to the rule of placing the entire plea agreement on the record. Sometimes, the defense, prosecutor and judge will work out a resolution of a high profile case, but will not want to place the terms of the deal on the record. (For example, the prosecutor may not want the adverse publicity of looking "soft on crime," and the judge may not want to admit to engaging in "sentence bargaining" in a serious case.) However, don't assume that your case falls into this small category of exceptions - ask your attorney before you plead guilty to make sure that the entire agreement is part of the record (either directly or by reference to the contract), and make the attorney explain any decision to depart from this practice.
The answer to that depends upon the facts of your case, and the laws and procedures of the jurisdiction where you are charged. However, in many cases it can be advantageous to retain an attorney and seek a plea bargain before you have been charged with an offense. For example, if your attorney can begin negotiations with a prosecutor while the police are still investigating or before you are formally charged with a crime, you may be able to obtain a reduction of charges that would not be available after charges are officially filed.