Animals in Scientific Research 391 evaluate the scientific aspects of the charges (American Medical Association 1946a) The manuscript included the following: The [human] experiment to be performed must be so designed and based on the results of animal experimentation and a knowledge of the natural history of the disease under study that the anticipated results will justify the performance of the [human] experiment (American Medical Association 1946b; Ivy 1946) These and other guidelines were subsequently adopted in the final version of the Nuremberg Code as well as in the World Medical Association Declaration of Helsinki (World Medical Association 1964) with the result that regulatory bodies such as the US Food and Drug Administration and the European Medicines Agency require animal testing on a rodent and non-rodent species in order to determine safe dose levels for human subjects taking part in clinical trials (US Food and Drug Administration 2010; European Medicines Agency 2008) Directive 2010/63/EU In addition to the pivotal role played by the Nuremberg code, European Directive 2010/63/EU provides a legal framework regarding the general use of animals in scientific procedures In terms of legislation, the focus of this chapter will be on the European Union (EU) in general and the UK in particular, whose national statistics are arguably among the most accurate and up to date on animal experiments, compared with the rest of the world For example, in the USA, the many millions of birds, rats and mice bred for scientific research purposes are not included in national statistics (United States Department of Agriculture, Animal Welfare Act 2013) Whereas animal based research was loosely regulated during the first half of the twentieth century, either through general animal protection laws or by a voluntary institutional code of ethics, the latter half of the twentieth century began to see the formulation of laws specifically covering animal experimentation An important contribution to the subject was the publication in 1959 of ‘The Principles of Humane Experimental Technique’ by two UK scientists, Russell and Burch, which enunciated the concept of the 3Rs: ‘reduction’ (the use of fewer animals, wherever possible), ‘refinement’ (the greater use of analgesics or the use of ‘lower’ organisms) and ‘replacement’ (the replacement of live animals with other methods) (Russell and Burch 1959)