The agreement was brokered in 1997 to resolve a trade embargo threatened by the EU in 1991 against countries that traded fur from wild animals caught by inhumane methods. The dispute had begun with pressure inside the EU from animal rights groups protesting against fur trade, focused particularly on the use of leg-hold traps. This backfired to some extent because fur-trading nations pointed out that similar traps were commonly used in EU countries to catch the same species (e.g. muskrat, coypu) or similar species as pests, and that no humaneness standards were applied there. Because fur trading was economically important — particularly for Canada and Russia, but also for some EU countries like Denmark and Iceland — and because pest control was also critical, a compromise was thrashed out: the AIHTS. This requires signatory countries to prohibit traps for fur-bearing species that will not pass a clearly specified humaneness test.
The AIHTS humaneness test was derived from discussions towards an international standard on humaneness in traps, a process which had been derailed by animal rights lobbyists within the technical working group, who ultimately asserted that no trap could ever be considered humane. The ISO standard salvaged from those failed discussions defined how to test traps but stopped short of defining a threshold for acceptability. An acceptability standard was defined in AIHTS. This reflects performance of the better traps available, but is nevertheless realistic.
AIHTS applies only to a list of species commonly caught in the wild for their fur. Of these, only otter, beaver, marten, badger and stoat occur in the UK, and under current UK law only stoat may be taken or killed without special licence. Notably missing from the AIHTS list are mink and fox. This is because fur from those species is mostly taken from fur farm stock, to ensure consistency, and to use variants that are rare in the wild. Weasel is also not listed: this is because it is not caught as a furbearer.
The AIHTS standard is not fixed, and it was anticipated that both the humaneness criteria and the list of species to which AIHTS applied would evolve in time.
A timeline for the evolution of AIHTS and its implementation by signatory countries can be found here.