 This system of binding interpretations or precedents evolved from the common law system (called "stare decisis"), where courts are bound by their own prior decisions and by the decisions of higher courts.While neither English common law courts nor continental civil law courts generally had the power to declare legislation unconstitutional (only the power to change law), the United States Supreme Court has long been understood to have the power to declare federal or state legislation unconstitutional.Before deciding a constitutional question, the Supreme Court may consider whether the court can avoid the constitutional question by basing its decision on a non-constitutional issue at dispute.