Piracy can claim the distinction of being the first crime to have been considered an international crime: in Cicero's terms, pirates were everyone's enemies hostes humani generis (De Officiis iii 29)
See also 1927 decision The ‘Lotus’ Case (France v Turkey) PCIJ Series A No 10
Piracy (International law) -- History
or try specific areas eg
Piracy -- English Channel region -- History
Piracy -- North Atlantic Region -- History
Policing - in territorial waters - then the right of hot pursuit
Hot pursuit (International law)
Prize Law
The capture at sea, in times of war, of the ships of enemies & their cargo, and in enemy goods in ships of other nations.
Privateers (privately owned crewed vessels) could sail under letters of marque so taking the war to (at least) the merchantmen of the enemy power. This was additional to the prize taking of regular navy ships.
For English privateers, Calendars of State Papers Domestic may record the issuing of warrants
'June 1649: An Act touching Letters of Marque.', in Acts and Ordinances of the Interregnum, 1642-1660 p 157
The treaty signed at the end of the Crimean War (1856 Declaration Respecting Maritime 114 CTS 409) that concluded the Crimean War (1853–56).
But contraband (goods which would help an enemy's war effort) could still be taken at sea, even if on the ship of a neutral country..
Subject searches to try in SOLO:
War, Maritime (International law);
Privateering
Prize courts
Prize law -- Cases
World War, 1914-1918 -- Prizes, etc
Contraband of War
Prize was the reward for capturing a slave ship.
Slavery Law and legislation Great Britain History
Slave-trade -- Africa -- History
Slave-trade -- West Indies, British -- History;
Power, Law and the End of Privateering by 
Ports, Piracy, and Maritime War by The HCA was, until the nineteenth century, a civilian court within a common law legal system. It heard both commercial and criminal case, as well as administering prize cases.