The Treaty of Rome, signed in 1957 by France, West Germany, Italy, Belgium, the Netherlands and Luxembourg, established the European Economic Community. The Treaty is the legal base which is periodically revised to take account of institutional and policy changes within the European Union. The Treaty of Rome did not include a reference to animal welfare. A revision resulted in the Treaty of Amsterdam which, thanks to Eurogroup campaigning, included a protocol on animal welfare. The Treaty of Amsterdam and the protocol became effective on 1 May 1999.

The animal welfare protocol included in the 1997 Treaty of Amsterdam is significant. For the first time in European law, animals are referred to as sentient beings - able to feel pain and suffering, and experience well-being.