The litigation process is governed by rules of civil procedure. Federal courts follow the federal rules of civil procedure, while state courts follow their own rules of civil procedure. The rules vary from state to state and even from court to court within the same jurisdiction, and they are essential to know because they mandate every step of litigation and set deadlines for filing pleadings and motions, as well as trial. Litigants, or their attorneys, must follow the rules to know what must be filed when, and if they do not, the case may not be successful at trial or the lawsuit may even be dismissed.

A lawsuit begins when a plaintiff files a complaint which sets forth the legal and factual reasons for the dispute, as well as what remedies the plaintiff (or plaintiffs) seek to recover from one or more defendants. After the plaintiff files the complaint with the court, the court issues a summons to notify the defendant of the lawsuit. The defendant may respond by filing an answer with the court which denies plaintiff's allegations and and sets forth his defenses. The complaint and answer are called pleadings and are usually written by attorneys, although in most courts, litigants can choose to represent themselves and write their own pleadings.

Any number of claims and defenses, based on numerous laws, may be brought within a single lawsuit. Plaintiffs and defendants can bring any number of cross-claims and counterclaims against each other, subject to certain rules of law, and can even bring additional parties into the suit after it begins.

Once the complaint and answer have been filed, the next phase of litigation is pre-trial. In order to prepare for trial, the parties participate in discovery, which is an ordered exchange of evidence and statements between the parties. The purpose of discovery is to avoid surprise at trial and clarify the legal and factual issues of the case. The discovery process allows parties to know how strong their cases are, depending on what evidence the other party produces and what witnesses say in depositions, when their sworn testimony is taken before a court reporter. Expert witnesses may be hired to give their opinions for each party.

The parties may also make motions to the court during the discovery process to include or exclude some legal issues or facts at trial. Litigants often reach a settlement during the discovery phase, especially as costs of litigation mount. If the parties do not settle the suit, it will go to trial.

A trial is an event in which parties to a dispute obtain resolution by presenting evidence and legal argument in a court before a judge, jury, or other designated finder of fact. A trial held only before a judge is called a bench trial, while a trial held before members of the community—in varying numbers from state to state—is called a jury trial. The judge or jury will hear testimony, view evidence, and make decisions to resolve the dispute.

The outcome will be affected by the standard of proof, or obligation to prove allegations that are charged. In civil trials, depending on the applicable law, the case must be proven either by "clear and convincing evidence," whereby the party with the burden of proof must convince the trier of fact that it is substantially more likely than not that the allegation is in fact true; or "preponderance of the evidence," which simply requires that the matter asserted seem more likely true than not.

Civil standards of proof are less strict than in a criminal trial, wherein the government must prove its case against the defendant "beyond a reasonable doubt." This can lead to very different results. For example, in a criminal trial, the Los Angeles County District Attorney could not prove beyond a reasonable doubt that O.J. Simpson was guilty of murder; however, in the subsequent civil trial, the victim's family was able to establish by a preponderance of the evidence—which is a lower standard of proof— that Mr. Simpson was liable for wrongful death.

After the judge or jury hears all the evidence, they will arrive at a decision regarding the individual claims set forth in the case. If the judge or jury finds for the plaintiff, it may then decide on the appropriate remedy or remedies, depending on the law applied. The remedy may be in the form of money damages or an equitable remedy, such as the issuance of an injunction to compel or prevent one party's actions. Usually the award is money, with the goal of putting the prevailing party in the same position it would have been in had the wrong not occurred.

After a final decision has been made, either party or both may appeal from the judgment if they are unhappy with it. The case will then go to an appellate court. Each jurisdiction has its own level of review by appellate courts, but all states and the federal government offer some form of appellate review. The appellate court will either affirm the judgment, refuse to hear the case, reverse, or vacate and remand the case, sending the lawsuit back to the trial court to address an unresolved issue. A whole new trial may be ordered, and the entire litigation process can thus take many years to finally reach a conclusion.