Canadian anti-whaling activist Paul Watson says Costa Rica made up charges

[kristopher]

1. There are several ways his activities could be considered criminal

The UN Convention on the Law of the Sea (UNCLOS) is probably the governing framework. It seems very unlikely they don't have a law covering the safety of vessels from attack or threats.

SECTION 3. INNOCENT PASSAGE IN THE TERRITORIAL SEA SUBSECTION A. RULES APPLICABLE TO ALL SHIPS

Article 17
Right of innocent passage

Subject to this Convention, ships of all States, whether coastal or land-locked, enjoy the right of innocent passage through the territorial sea.

Article 18
Meaning of passage

1. Passage means navigation through the territorial sea for the purpose of:
(a) traversing that sea without entering internal waters or calling at a roadstead or port facility outside internal waters; or
(b) proceedingtoorfrominternalwatersoracallatsuchroadstead or port facility.
2. Passage shall be continuous and expeditious. However, passage includes stopping and anchoring, but only in so far as the same are incidental to ordinary navigation or are rendered necessary by force majeure or distress or for the purpose of rendering assistance to persons, ships or aircraft in danger or distress.

Article 19
Meaning of innocent passage

1. Passage is innocent so long as it is not prejudicial to the peace, good order or security of the coastal State. Such passage shall take place in conformity with this Convention and with other rules of international law.
2. Passage of a foreign ship shall be considered to be prejudicial to the peace, good order or security of the coastal State if in the territorial sea it engages in any of the following activities:
(a) any threat or use of force against the sovereignty, territorial integrity or political independence of the coastal State, or in any other manner in violation of the principles of international law embodied in the Charter of the United Nations;
(b) anyexerciseorpracticewithweaponsofanykind;
(c) any act aimed at collecting information to the prejudice of the
defence or security of the coastal State;
(d) anyactofpropagandaaimedataffectingthedefenceorsecurity
of the coastal State;
(e) the launching, landing or taking on board of any aircraft; (f) the launching, landing or taking on board of any military
device;
(g) the loading or unloading of any commodity, currency or person
contrary to the customs, fiscal, immigration or sanitary laws and
regulations of the coastal State;
(h) any act of wilful and serious pollution contrary to this
Convention;
(i) any fishing activities;
(j) the carrying out of research or survey activities;
(k) any act aimed at interfering with any systems of communication or any other facilities or installations of the coastal State;
(l) any other activity not having a direct bearing on passage.

Article 20
Submarines and other underwater vehicles

In the territorial sea, submarines and other underwater vehicles are required to navigate on the surface and to show their flag.

Article 21
Laws and regulations of the coastal State relating to innocent passage

1. The coastal State may adopt laws and regulations, in conformity with the provisions of this Convention and other rules of international law, relating to innocent passage through the territorial sea, in respect of all or any of the following:
(a) the safety of navigation and the regulation of maritime traffic;
(b) the protection of navigational aids and facilities and other facilities or installations;
(c) the protection of cables and pipelines;
(d) the conservation of the living resources of the sea;
(e) the prevention of infringement of the fisheries laws and regulations of the coastal State;
(f) the preservation of the environment of the coastal State and the prevention, reduction and control of pollution thereof;
(g) marine scientific research and hydrographic surveys;
(h) the prevention of infringement of the customs, fiscal, immigration or sanitary laws and regulations of the coastal State.

2. Such laws and regulations shall not apply to the design, construction, manning or equipment of foreign ships unless they are giving effect to generally accepted international rules or standards.
3. The coastal State shall give due publicity to all such laws and regulations.
4. Foreign ships exercising the right of innocent passage through the territorial sea shall comply with all such laws and regulations and all generally accepted international regulations relating to the prevention of collisions at sea.

http://www.un.org/depts/los/convention_agreements/convention_overview_convention.htm