“Litigation” is the term used to describe the legal process by which one party, a plaintiff or complainant, seeks a remedy for damages caused by another, commonly called a defendant. Any proceeding in a court of law where two parties are in an adversarial relationship is litigation. While any issue in the law can be a type of litigation, the two main types are criminal litigation and civil litigation. Criminal litigation cases involve defendants who are alleged to have violated criminal statutes. In a civil litigation cases, a lawsuit is brought by one party against another without any allegation that a crime has been committed.
In criminal cases, the complainant is usually described as “the people,” and a district attorney or a US Attorney represents them in seeking a remedy — often imprisonment of the defendant or some other punishment such as payment of a fine. Criminal litigation cases where there's a possibility that the death penalty may be imposed can be called capital litigation cases.
In civil litigation cases, there must be some damage suffered by the plaintiff, alleged to have been caused by the defendant. For example, when a doctor is sued for medical malpractice, that's a form of civil litigation. If a person sues her neighbor because of damages claimed as a result of the neighbor's negligent snow removal, that's also civil litigation. When a manufacturer is sued because of damage caused by a faulty product, that's another form of civil litigation case called a product liability lawsuit. Other relatively common types of litigation are copyright litigation, which usually involves a claim of violation of intellectual property rights; debt litigation, in which a creditor files suit against a debtor; and commercial litigation, which encompasses a broad array of issues such as breach of contract, employment disputes and shareholder issues, to name but a few.
In civil litigation cases, the plaintiff seeks to recover the cost of repairing the damage alleged to have been done by the plaintiff, and often additional money damages as well, called “pain and suffering” or “punitive damages.” Either side can demand a jury trial, or both may agree to a non-jury trial in which the judge will render the verdict and, if necessary, an award. Each side will present its case in court, at the end of which the verdict is rendered and, if it's in the plaintiff's favor, an award as well. Due to the sometimes enormous sums of money involved, and the intricacies of the law, plaintiffs and defendants alike will often hire attorneys who specialize in that particular type of litigation. While all attorneys learn to litigate during their academic training, not all are very good at it, and many attorneys will practice law for their entire careers without ever arguing a case in front of a judge and jury.
A particular type of civil litigation worthy of mention is class action litigation. A class action can be declared when a number of plaintiffs allege that the same defendant has damaged them all in the same way. For example, if a number of owners of a particular make and model of automobile are all injured in accidents that can all be traced to some problem in the automobile's manufacture, the attorneys may petition the judge to declare the plaintiffs a “class,” and commence legal action – in this case, a product liability lawsuit - on behalf of that class. Class action lawsuits can aid the administration of justice in the United States by consolidating a number of similar or identical lawsuits, all of which might take months or years to adjudicate on their own, into a single action, all to be decided as a single case.
It's not necessary that either party to civil or criminal litigation cases be a citizen or even a natural person: companies can sue each other, governments can sue each other, and companies and governments can sue each other. Any entity recognized under the law can be a party to, and any issue addressed in the law can be a cause addressed by litigation cases.