Legal foundations

Every group of people needs some way to organise behaviour. A rule is a guide to conduct made by a group, organisation or family for its own members, such as a school uniform policy or a sporting club's code of conduct.

A law is a rule made or recognised by a body with legal authority, such as a parliament or a court, and it applies to everyone within the jurisdiction, meaning the geographical area or subject matter over which a law-making body or court has authority. The key differences lie in source, reach and enforcement.

Breaking a school rule might lead to a detention, but breaking a law can lead to action by the state through police, courts and penalties such as fines or imprisonment.

Laws serve several purposes. They maintain order by setting standards of acceptable behaviour; they protect people, property and rights; they provide a peaceful way to resolve disputes instead of self-help or revenge; they limit the power of government; and they reflect, and sometimes help shape, community values.

Criminal law deals with crime: conduct the state treats as harmful to society as a whole, so the state, through the police and prosecutors such as Queensland's Office of the Director of Public Prosecutions, rather than the individual victim, investigates and prosecutes it and can punish the offender.

Not every law works well. An effective law generally has these characteristics:

• it is known to the public, because people cannot obey a law they cannot find or understand
• it is acceptable to the community, reflecting current values so most people comply voluntarily
• it is enforceable, meaning police and courts can detect breaches and apply consequences
• it is clear and stable, and it carries specific penalties that apply to everyone equally

When a law loses community acceptance or cannot be enforced, pressure usually builds for parliament to change it. These characteristics also give you a checklist for analysing whether an existing or proposed law is likely to work.