The doctrine of OPINIO JURIS in international law is distinct from STATE PRACTICE in that opinio juris is:

1. State practice (the OBJECTIVE element) is the empirically observable conduct of States. 2. Opinio juris (the SUBJECTIVE element) is the belief or conviction of States that a practice is followed because it is required by law (not merely habit, comity, or convenience). 3. Both elements are essential to establishing a rule of customary international law. 4. The ICJ in North Sea Continental Shelf required clear evidence of opinio juris, not just frequency of practice. 5. Hence option B is correct. _Source: UN Charter 1945 / Vienna Convention on Law of Treaties 1969 / ICJ Statute / ARSIWA 2001 — ICJ Statute Article 38(1)(b); North Sea Continental Shelf (1969)_