The international regime for carriage of passengers and goods by air, which replaced the Warsaw system and introduced two-tier liability.
The Montreal Convention of 1999 ended a stack that had become unreadable: the Warsaw system of 1929, patched by five protocols and two private agreements, was no longer applied the same way by neighboring states. In force since November 4, 2003 and ratified by almost every country that matters in world traffic, it unifies transport documents, admits the electronic air waybill and fixes time limits and competent courts. Its central contribution is two-tier liability for passenger injury, replacing a single ceiling with strict liability up to a threshold and presumed fault liability above it, without cap. It adds a fifth jurisdiction, that of the passenger's principal residence, which gave families a remedy in their own country. The problem solved is that of a victim whose compensation depended on the route chosen and on the accidents of ratification rather than on the harm suffered.
The liability limit for carried goods rose from 17 special drawing rights per kilogram originally to 19 in 2009, 22 on December 28, 2019 and 26 on December 28, 2024: for a 300 kilogram pallet of electronic components the cap therefore stays below 8,000 special drawing rights whatever the real value, which makes cargo insurance a necessity rather than an option.
MC99, convention pour l'unification de certaines règles du transport aérien