Human rights experts say the attack on the ship was likely illegal according to international law and the customary law of the sea, noting that Israeli justifications in claims that the activists were armed do not render their actions legal.
"In international waters, the crew of a ship have the right to prevent others from boarding their ship without their permission; including by resorting to force," human rights and international law expert at the Al-Mezan Center for Human Rights in Gaza Mahmoud Abu Rahma told Maan News Agency.
States can only act within a 12 nautical miles, in the marine zone along their shores, the lawyer said, adding that "States are of course entitled to act in self-defense under certain limitations."
Reports indicate that the Israeli attack on the ship took approximately 34 nautical miles off the shore of the Gaza Strip, rendering the incident an international matter in international waters.
"There are several questions to consider," the Abu Rahma said. "One is whether Gaza is occupied or not. If not, then Israel has absolutely no right to act inside or outside its nautical jurisdiction."
Israel claims that it unilaterally pulled out of Gaza in 2005, and says the move constituted an end to the country's occupation of the coastal enclave. However, the nation maintains a land and sea blockade, along with Egypt, and took control of a 300-meter "buffer zone" along Gaza's parameter, constituting some 20% of the arable land in the Strip.
If indeed Israel insists that it does not occupy Gaza, that the attack was "a serious violation of international law," Abu Rahma said.
The second question, Abu Rahma said, is whether or not Israel acted in self-defense, noting that a legal decision would also depend on whether or not Israel occupies Gaza.
"Self-defense rules limit states right to use military force to situations where there is an actual threat that has already materialized and there is no option to deter it except throughout resort to military force," the lawyer said quoting Article 51 in the UN Charter. "Apparently, we are before a case where a group of civilians are on board of civilian cargo and passenger ships. This is nothing like an imminent military attack that has materialized and requires resorting to military force to deter it," he said.
The third issue determining the legality or illegality of the events would be under regional and international law enforcement. "Military or police forces may not use force except to the extent necessary to deal with a certain situation," Abu Rahma said, adding that "given the very high number of casualties and injuries, there is a strong suspicion that a high amount of excessive, lethal force has been employed."
The final issue, and perhaps the one with the largest ramifications for Israel, Abu Rahma said, is the issue of the rights and sovereignty of the states under whose flags the ships were sailing when they were attacked, particularly since the incident was in international waters.