The IWC is responsible for setting catch limits for commercial whaling (with the exceptions of Norway and Iceland, see below). The Commission receives advice on sustainability from its Scientific Committee before deciding catch limits, which are then set out in a document called the Schedule to the International Convention for the Regulation of Whaling.
In 1982 the IWC decided that there should be a pause in commercial whaling on all whale species and populations from the 1985/1986 season onwards. This pause is often referred to as the commercial whaling moratorium, and it remains in place today.
The discussions and decision-making process are recorded in the report of the 1982 meeting and you can read it here (agenda item 6). There is also a Verbatim Record of the meeting and you can read that transcript here. Scroll to p72 for the start of the relevant discussion (agenda item 6). This issue was considered over a period of several years before the decision was taken in 1982. Earlier discussions are also recorded in the relevant meeting reports and these are all available on the IWC archive.
In recent years, Norway and Iceland have caught whales commercially. The Government of Norway lodged a formal objection to the moratorium decision when it was introduced. Iceland left the IWC in 1992 and re-joined in 2002 with a reservation to the moratorium. When the moratorium was introduced, the Russian Federation also registered an objection but does not exercise it. The moratorium is binding on all other members of the IWC.
Norway and Iceland establish their own catch limits but must provide information on their catches and associated scientific data to the Commission. Norway takes North Atlantic common minke whales within its Exclusive Economic Zone, and Iceland has taken North Atlantic common minke whales and also North Atlantic fin whales, again within its Exclusive Economic Zone, although Iceland has not caught whales since 2018.
Japan left the IWC in 2019 and began to catch whales commercially the same year. Having left the IWC is no longer bound by the moratorium. Japanese catches are also reported to the IWC.