Common law and equity are systems of law whose sources are the decisions in cases by judges. In addition, every system will have a legislature that passes new laws and statutes. The relationships between statutes and judicial decisions can be complex. In some jurisdictions, such statutes may overrule judicial decisions or codify the topic covered by several contradictory or ambiguous decisions. In some jurisdictions, judicial decisions may decide whether the jurisdiction's constitution allowed a particular statute or statutory provision to be made or what meaning is contained within the statutory provisions. The common law developed in England, influenced by Anglo-Saxon law and to a much lesser extent by the Norman conquest of England, which introduced legal concepts from Norman law, which, in turn, had its origins in Salic law. Common law was later inherited by the Commonwealth of Nations, and almost every former colony of the British Empire has adopted it (Malta being an exception). The doctrine of "stare decisis", also known as "case law" or "precedent by courts", is the major difference to codified civil law systems.