General average

The law of general average is a legal principle of maritime law according to which all parties in a sea venture proportionally share any losses resulting from a voluntary sacrifice of part of the ship or fleet to save the whole in an emergency. In the exigencies of hazards faced at sea, crewmembers often have precious little time in which to determine precisely whose cargo they are jettisoning. Thus, to avoid quarrelling that could waste valuable time, there arose the equitable practice whereby all the merchants whose cargo was on board would be called on to contribute a portion, based upon a share or percentage, to the merchant or merchants whose goods had been tossed overboard to avert imminent peril. While general average traces its origins in ancient maritime law, still it remains part of the admiralty law of most countries.
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A general loss voluntarily incurred to save all interest involved in a common maritime adventure from an impending peril including hull, cargo, and freight at risk. (TNDOT1)

Ancient principle of equity in which all parties in a sea adventure (ship, cargo, and freight) proportionately share losses resulting from a voluntary and successful sacrifice of part of the ship or cargo to save the whole adventure from an impending peril, or extraordinary expenses necessarily incurred for the joint benefit of ship and cargo.

AVARIA GENERALE. AVARIA COMUNE