The Eastern Caribbean Supreme Court, established on St. Lucia, administers the judicial system, which is based on English common law and statutory acts of the House of Assembly. A puisne judge of the Court is responsible for St. Kitts and Nevis and presides over the Court of Summary Jurisdiction.

Magistrates' courts deal with petty criminal and civil cases. The attorney general is the government's principal legal adviser. An appeal may be taken to the organization of Eastern Caribbean States Court of Appeal; until 2003, final appeals were taken to the Judicial Committee of the Privy Council in the United

Kingdom. St.Kitts and Nevis was among the nations joining together to form the Caribbean Court of Justice (CCJ) to hear cases formerly taken to the Privy Council.