This case involved the transportation of cocaine on a yacht. The plan was that the appellants AA and BB, crewing the yacht, would deliver the cocaine at an undetermined point on the high seas in the North Sea. The yacht came to the notice of the Portuguese Navy and Air Force, and the necessary operational steps were immediately initiated. Contact was made with the relevant flag State authorities pursuant to art 17 of the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances 1988, in order to obtain authorisation to carry out boarding and inspection of the yacht at sea. However, the authorities responded that the registration certificate of the yacht had already expired.

On 19 January 2020, the Portuguese Navy boarded the yacht and verified that it was sailing without an effective flag, ie was without nationality. The yacht was detained and taken to national territory by the Portuguese Navy. The appellants were subsequently convicted for drug trafficking offences. They appealed to the Court of Appeal, arguing, among other things, that as the Portuguese authorities were not in possession of authorisation from the competent flag State authorities, art 18 of Law No 34/2006 of 28 July, and arts 27.3 and 27.5 of UNCLOS were violated.

Article 27 of UNCLOS governs criminal jurisdiction on board a foreign ship:

3. ... [T]he coastal State shall, if the master so requests, notify a diplomatic agent or consular officer of the flag State before taking any steps, and shall facilitate contact between such agent or officer and the ship's crew. In cases of emergency this notification may be communicated while the measures are being taken. ...

5. Except as provided in Part XII or with respect to violations of laws and regulations adopted in accordance with Part V, the coastal State may not take any steps on board a foreign ship passing through the territorial sea to arrest any person or to conduct any investigation in connection with any crime committed before the ship entered the territorial sea, if the ship, proceeding from a foreign port, is only passing through the territorial sea without entering internal waters.

Held: Convictions upheld; sentences varied.

As to the UNCLOS argument, at the time when the Portuguese Navy boarded the yacht, it was in the presence of a vessel that was not flying a flag - a stateless vessel, without nationality. For this reason, the Navy acted in compliance of the procedures set out in art 17 of the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances 1988, and art 110.1.d of UNCLOS, which provides that a warship which encounters a foreign ship on the high seas is justified in boarding it if there is reasonable ground for suspecting that the ship is without nationality. The approach taken by the Navy vessel and the acts that followed, namely the yacht's transport to national territory, were not carried out in disregard of any legal provision.