For most people, the law becomes real in a courtroom, or in the shadow of one. This level explains the main kinds of cases, the two great styles of trial, and what happens after a verdict. Details vary by country; the aim here is the shared logic.
Criminal and civil cases
A criminal case is brought by the state against a person accused of a wrong against society, and it can end in punishment such as a fine or prison. A civil case is a dispute between parties, often private ones, in which the claimant seeks a remedy such as compensation (damages) or a court order. Contracts, accidents, property and family disputes are usually civil matters. The same event can lead to both: a driver who injures someone while drunk may be prosecuted and also sued.
Burden and standard of proof
The burden of proof says who must prove the case; the standard of proof says how convincingly. In criminal cases the prosecution bears the burden, and in common law countries it must prove guilt beyond reasonable doubt. In civil cases the claimant usually needs to prove the case only on the balance of probabilities, called the preponderance of the evidence in the United States: more likely than not. The higher criminal standard reflects how much more is at stake when the state seeks to punish. This is why a person can be acquitted of a crime and still be found liable for the same act in a civil case.
Adversarial and inquisitorial trials
Common law countries use an adversarial system. Each side gathers and presents its own evidence and questions witnesses, and the judge acts mainly as a neutral umpire who enforces the rules. Supporters say a clash of committed advocates is a good way to test evidence. Critics say outcomes can depend too much on the skill and cost of lawyers.
Many civil law countries, such as France and Germany, use a more inquisitorial system. The judge takes an active role in investigating the facts and questioning witnesses, often working from a written file assembled before trial. Supporters say this focuses the process on finding the truth. Critics worry that it places great power in officials and that the file may shape the outcome before trial. In practice every system mixes elements of both.
Juries and lay judges
In many common law countries, serious criminal trials can be decided by a jury of ordinary citizens, who decide the facts while the judge decides questions of law; the United States also uses juries in many civil cases. Many civil law countries instead seat lay judges who sit alongside professional judges and decide together. Japan introduced such a mixed panel, the saiban-in system, in 2009. Defenders of lay participation say it brings community values and democratic legitimacy into justice; critics question whether untrained people can handle complex evidence.
Not every case goes to trial
Most civil cases settle, and in many systems most criminal cases end in a guilty plea, sometimes after negotiation with the prosecution. Trials are the visible tip of a much larger process.
Appeals
A party who loses may usually appeal to a higher court. Appeals generally review errors of law or procedure rather than rehearing all the evidence, since the trial court saw the witnesses. An appeal court may confirm the decision, reverse it, or send it back for a new hearing. The highest court in a system settles disputed questions of law for all lower courts.
Worked example: one accident, two cases
Mara is cycling home when a car runs a red light and knocks her down, breaking her arm. Witnesses say the driver, Theo, had been drinking. Two separate legal processes may follow.
The criminal case. The police investigate, and the state prosecutes Theo for dangerous driving while impaired. Mara is a witness, not a party. In a common law country, the prosecution must prove each element beyond reasonable doubt. Theo's lawyer challenges the breath test, arguing the device was not properly calibrated. The jury is left with real doubt about his level of impairment and acquits him of that charge, though he is convicted of running the red light.
The civil case. Mara sues Theo for her medical bills and lost wages. Here she is the claimant and must prove only that it is more likely than not that Theo's careless driving caused her injury. The witnesses and the traffic camera easily meet that standard. The court awards damages, though most likely the case settles first, with Theo's insurer paying.
The appeal. Suppose Theo appeals his conviction, arguing that the trial judge wrongly allowed some evidence. The appeal court will not hear the witnesses again; it will ask whether the judge made an error of law and whether it affected the result.
If the same events had occurred in an inquisitorial system, the investigating judge or court would have taken a more active role in gathering the evidence, and the trial would rely more heavily on the written file.