According to common doctrine, the courts, once established, apply the constitution, the principles expressed in the constitution, and also some principles not always expressed but that are thought to be inherent to any legal system, as for example the principle that the State is sovereign. Like the hierarchy of norms, these principles precede the institution of the courts and their jurisprudence, so that they can be used to evaluate them. True, the principles can be vague, but it is considered one of the tasks of constitutional theory to determine their substance before analyzing case law in their light.
Judicial Review and International Law,
San Diego Int'l L.J.
Available at: https://digital.sandiego.edu/ilj/vol4/iss1/4