The doctrine of precedent, or stare decisis, lies at the heart of the English legal system. The doctrine refers to the fact that within the hierarchical structure of the English courts, a decision of a higher court will be binding on a court lower that it in that hierarchy. In general terms this means that when judges try cases they will check to see if a similar situation has come before a court previously. If the precedent was set by a court of equal or higher status to the court deciding the new case, then the judge in the present case should follow the rule of law established in the earlier case. Where the precedent is from a lower court in the hierarchy, the judge in the new case may not follow but will certainly consider it. .
It is noted that the doctrine of precedent depends for its operation upon the underlying principle that the courts form a hierarchy with each court standing in a definite position in relation to every other court. The structure of this hierarchy must now be considered for the purposes if the doctrine of precedent. Decisions of the highest courts are binding on lower courts. .
The House of Lords decisions are binding on all other courts in the legal system, except the House of Lords itself. The House of Lords was bound by its own previous decisions until it changed this practice in 1966. The old practice had been established in the 19th Century and was reaffirmed in a famous case London Tramways Co Ltd v London County Council. The rule however did not appear to create certainty and had become very rigid by the end of the 19th Century. The practice was eventually changed in July 1966 when Lord Gardiner, the Lord Chancellor, made a statement on behalf of himself and his fellow lords to the effect that their Lordships proposed in future to depart from their own previous decisions. Since 1966, the House of Lords has used this power quite sparingly. It will not refuse to follow its earlier decision merely because that decision made was wrong.