What is criminal law?
Criminal law is the part of law that says which acts are crimes and what punishment they get.
A crime is seen as a wrong against society as a whole, not just the victim. So the state brings the case (the prosecution), not the victim.
This is different from civil law, where one person sues another, for example for a broken contract, and asks for money (compensation).
Main ideas in most countries: no crime without a law (an act is only a crime if a law said so before it happened); punishment should fit the crime; the accused is presumed innocent.
The elements of a crime: actus reus and mens rea
Actus reus (Latin: guilty act) is the physical part: an action, sometimes a failure to act when there is a duty (like a parent not feeding a baby), plus the result it causes.
Mens rea (guilty mind) is the mental part: intention (wanting the result) or recklessness (seeing a risk and taking it anyway). For some minor offences, negligence (careless, below a reasonable standard) is enough.
Causation: the act must actually cause the harm.
A few strict liability offences, like many traffic and food-safety rules, need no guilty mind at all.
Offences against the person: fatal and non-fatal
Fatal offences (someone dies):
- Murder: unlawful killing with intention to kill or cause serious harm. The most serious offence.
- Manslaughter / culpable homicide: unlawful killing without the full intention of murder, for example a death from a dangerous unlawful act or gross negligence, or where a partial defence (like loss of control) applies.
Non-fatal offences (injury but no death), from least to most serious: assault (making someone fear immediate force), battery (unlawful touching or force), causing actual bodily harm, causing serious (grievous) bodily harm, with or without intent.
Property offences
- Theft: dishonestly taking property that belongs to another, meaning to keep it permanently.
- Robbery: theft using force or the threat of force.
- Burglary: entering a building as a trespasser to steal or cause harm.
- Fraud: getting money or property by lying or tricking (including online scams).
- Criminal damage: destroying or damaging someone's property on purpose or recklessly (like vandalism).
Attempts and other incomplete crimes
An attempt is when a person, with intention to commit a crime, does an act that is more than merely preparing but the crime is not completed.
Buying a crowbar is preparation. Forcing a window open is an attempt at burglary.
Other incomplete crimes: conspiracy (agreeing with others to commit a crime) and encouraging or assisting a crime.
Defences
- Self-defence / private defence: using reasonable force to protect yourself, others or property.
- Duress: being forced by a serious threat of death or injury.
- Insanity: a mental illness so severe that the person did not know what they were doing or that it was wrong.
- Intoxication: rarely a full defence; being drunk by choice usually does not excuse.
- Consent: works for some minor contact (like sport) but not for serious harm.
Full defences lead to acquittal. Partial defences reduce murder to manslaughter.
Legal responsibility and youth criminal law
Children below the age of criminal responsibility cannot be convicted. The age differs: for example 7 in India (with a test of understanding up to 12), 10 in England, 14 in Germany and Korea.
Young people above that age are usually dealt with by juvenile or youth courts. The aim is education and rehabilitation more than punishment: warnings, community work, counselling, and only rarely detention. Their names are usually kept private.
Criminal procedure and the rights of the accused
Typical path: crime reported → police investigation → arrest → charge → trial → verdict → sentence → appeal.
Rights found in most legal systems: to be told why you are arrested; to remain silent; to a lawyer (free if you cannot pay); to be brought before a judge quickly; to a fair, public trial; to be presumed innocent; guilt must be proved beyond reasonable doubt; not to be tried twice for the same crime.
Punishments include fines, community service, probation and imprisonment. Their aims: deter, protect society, reform the offender and repair the harm.
Try it
Be the judge: in the 3D free play, pick each case. Before you look, write down: Is there a guilty act? A guilty mind? A defence? Then check the lights. Try making your own case and test it with A + M − D.
Key formulas and definitions
- Crime = actus reus (guilty act) + mens rea (guilty mind)
- Mens rea levels: intention > recklessness > negligence
- Murder = unlawful killing + intent to kill or cause serious harm
- Theft = dishonest taking + property of another + intent to keep
- Robbery = theft + force
- Attempt = intent + act beyond mere preparation
- Burden of proof: prosecution, beyond reasonable doubt
Worked examples
1. Asha picks up an umbrella from a café stand, honestly believing it is hers. Is it theft?
There is a taking (actus reus), but no dishonesty, so no mens rea for theft. It is not theft. She should return it when she finds out.
2. Ravi pushes a man during an argument. The man falls, hits his head and dies. Ravi did not want to kill or seriously hurt him. Murder or manslaughter?
The push is an unlawful act that caused death, but there was no intention to kill or cause serious harm. This is manslaughter (culpable homicide not amounting to murder), not murder.
3. Sam climbs through an open window at night to steal a laptop but is caught in the hallway. What offences?
Entering as a trespasser with intent to steal is burglary, which is complete as soon as he enters. Taking the laptop was not finished, so it is also attempted theft.
Common mistakes
- Thinking the victim prosecutes a crime. In criminal cases the state prosecutes; the victim is a witness.
- Thinking any killing is murder. Murder needs intention; without it the offence is usually manslaughter.
- Confusing robbery and burglary. Robbery needs force on a person; burglary needs entering a building as a trespasser.
- Thinking the accused must prove innocence. The prosecution must prove guilt beyond reasonable doubt.