The doctrine of precedent states that a court has to follow legal rules set in earlier cases when deciding cases. Judges make legal rules when deciding cases. Judges can only make laws when cases are brought before them. This is where the term ‘judge made law’ came from. A judge cannot make laws just because he or she feels like. An appropriate case has to come before the judge for the judge to decide on the case. Once that case is decided, all courts that are lower in hierarchy have to follow this decision when a similar case comes before them.
Here is an example of how precedent applies in daily life.
Mary is a mother with a teenage son Tom. Tom comes home from school and throws his dirty school uniform on the floor. Mary, seeing what Tom had done, tells Tom that he will not be allowed to play computer games for a week.
The rule is that Tom will not be allowed to play computer games if he throws dirty clothes on the floor. In legal terms, this is called a precedent.
Judges, just like mothers, need to set rules. They also need to be consistent when deciding on similar cases.
Going by this principle and back to our daily life example, computer games are not allowed if dirty clothes are thrown on the floor. This applies to dirty clothes whether it is school uniform, football attire, or clothes worn when going out with friends.
The difference with this daily life example as compared to the court system is that there are many judges and courts as compared to one mother and one household. To be consistent when deciding cases, the legal rules set by higher courts are applied to all courts that are lower in hierarchy in the same court system. The judges in lower courts are obliged to follow the precedents that are set by judges in the higher courts.
The Ratio Decidendi is the central legal rule from a judgement. The ratio is the part of the judgement that becomes the precedent.
The ratio in our daily life example is that dirty clothes must not be thrown on the floor.
Obiter Dicta (singular) or Obiter Dictum (plural) are the other comments by the judges about the law but they do not decide the case before them.
Let us go back to the daily life example again to explain this.
Supposed that Mary tells Tom, “You are not allowed to play computer games for a week because you threw your dirty school uniform on the floor. Also, if you do not do your homework, I am not giving you your pocket money for next week.”
Tom is perplexed because he did do his homework. The only thing he did wrong was to throw his dirty school uniform on the floor. However, if Tom fails to do his homework a month from the incident, Mary can refer back this rule she previously made in the case of the dirty school uniform and not give Tom his pocket money for the following week.
The obiter dicta in this instance is that if homework is not completed, pocket money will not be given for the following week.