/ʌnˈrɪtən kɒnstɪˈtʃuːʃənl lɔː/ – Pharse
Definition: hiến pháp không thành văn.
A more thorough explanation: Unwritten constitutional law refers to principles, practices, and norms that are not explicitly codified in a written constitution but are nonetheless considered to be fundamental to the functioning of a legal system. These unwritten constitutional principles may be derived from historical practices, judicial decisions, conventions, and other sources of constitutional authority. They are often seen as essential components of the constitutional framework of a country, even though they are not formally written down in a constitution.
Example: In the United Kingdom, the doctrine of parliamentary sovereignty is a cornerstone of the unwritten constitution. This principle states that Parliament has the ultimate authority to make or unmake any law. While not explicitly stated in a written constitution, this doctrine has been upheld through centuries of legal practice and judicial decisions.