A lawsuit requires two opposing parties, a plaintiff and a defendant. The plaintiff is the complaining party, and the defendant is the party who attempts to protect himself from allegations. In most legal systems, the plaintiff bears the burden of proof. The defendant commonly has rights such as to remain silent and to refuse to incriminate herself.
Some cases involve a disagreement of facts. For example, a plaintiff may claim that an individual is the one who attacked her, and he, as the defendant, may argue that he is not the attacker. In some cases, however, a plaintiff and a defendant agree on the facts but engage in an argument regarding how the law affects those facts. Such an example may arise in a contract dispute where both parties agree that a certain clause exists but disagree as to the legal implications that it has for each of them.
In either instance, the plaintiff is someone who makes an allegation. An individual, a business, or a government entity may act as a plaintiff. Despite who the plaintiff is, for her case to be valid for handling by a court her complaint must be based on a violation of law. When filing a case, she will generally be required to specify the grounds that she believes make her matter a legal issue. If there is insufficient evidence to establish a viable argument or if she is arguing on grounds that are not supported by current laws, the case cannot proceed.
When there is sufficient reason to suggest that perhaps the plaintiff has a valid claim, she bears the burden of proof. This means that she must show evidence that convinces the court that the violation of law actually occurred. The amount of proof that she must show can vary from one jurisdiction to another. In some court systems, for example, it may be necessary to only display proof beyond a reasonable doubt. In other court systems, a person may need absolute proof.
A defendant may also be an individual, a business, or a government entity. The role of the defendant is drastically different, however. In a lawsuit, the defendant’s aim is to disprove the allegations against him. A major difference between a plaintiff and a defendant is that the plaintiff must present a case. Technically, a defendant could remain silent in a lawsuit and merely leave the burden on the plaintiff.
For a defendant to proceed through a lawsuit without presenting any evidence or arguments is not a common strategy. It tends to be highly ineffective and plagued with risk. Instead, it is most common for a plaintiff and a defendant to be actively engaged in disproving or weakening any evidence presented by the opposition. Even when doing this, a defendant does not have to testify on his own behalf.