Perhaps the oldest of the laws of the sea is the prohibition of
piracy, as the peril of being set upon by pirates, who are not motivated by national
allegiance, is shared by the vessels and mariners of all nations, and thus represents a crime upon all nations. Since
classical antiquity, pirates have been held to be individuals waging private warfare, a private campaign of
sack and
pillage, against not only their victims, but against all nations, and thus, those engaging in piracy hold the particular status of being regarded as , the enemy of humanity. Since piracy anywhere is a peril to every mariner and ship everywhere, it is held to be the universal right and the universal duty of all nations, regardless of whether their ships have been beset by the particular band of pirates in question, to capture, try by a regularly constituted
court-martial or
admiralty court (in extreme circumstances, by means of a
drumhead court-martial convened by the officers of the capturing ship), and, if found guilty, to
execute the pirate via means of
hanging from the
yard-arm of the capturing ship, an authoritative
custom of the sea. Although summary battlefield punishment was conducted by certain nations at certain times with regard to pirates, it was regarded as irregular, as individuals captured with pirates could potentially have a defense to charges of piracy, such as
coercion. Nonetheless, it was regarded as lawful if the attenuation of due process was dictated by urgent military necessity. For instance, in early 1831, the 250-strong crew captured off
Ascension was brought to Ascension and summarily hanged, as they were acting in a rebellious manner and threatening to overthrow the 30-man crew of , a British sloop-of-war, which took them captive. As the summary punishment, in this case, was due to military necessity, there was clear evidence of the offense, and it was done proximate in time and location to the battlefield, it can be classified as merely irregular, and not a violation of the custom of the sea. ==Theorized extended usages of the term==