A Look at the 3Rs
Research Models
Marilyn Brown

A Look at the 3Rs

Russell and Burch

In the mid-1950s, zoologist William Russell and microbiologist Rex Burch were hired by an animal welfare organization in the UK to study humane techniques for laboratory animal experiments. After five years of research they published their findings in a book entitled, The Principles of Humane Experimental Technique (1959).

In it, they put forth a comprehensive, ethical approach to the use of animals in research. They also proposed what are known as the 3Rs: Replacement, Reduction and Refinement. Replacement urges the use of alternatives to animals wherever possible. Reduction stresses using the least number of animals wherever appropriate. And Refinement calls for the modifications to experimental procedures and study designs so as to minimize potential animal pain or distress. The 3Rs set the standard for minimizing animal use and maximizing animal well-being in laboratory experimentation. 

A Moral Imperative (and Good Science)

In their book, Russell and Burch claimed it was the moral duty of researchers to employ the 3Rs. Researchers agreed. And the new perspective led to a better understanding of living conditions and handling procedures. The two scientists also emphasized the 3Rs equated to good science. Researchers agreed on this point as well, knowing that animal health did impact the quality of research. Data from a stressed animal, for example, can often be inaccurate and therefore affect its translation to humans.


After The Principles of Humane Experimental Technique was published in 1963, the First Guide for the Care and Use of Laboratory Animals was released (the second edition of The Guide came out in 1968). The concept of alternatives started gaining momentum in the 1970’s. The Journal of Alternatives to Laboratory Animals was also published around this time. The National Academy of Science (NAS) held its first major scientific meeting on the topic of animal alternatives and the 3rd and 4th edition of The Guide were released as well.

In the 1980s, governments and academia become more involved. The Center for Alternatives to Animal Test (CAAT) was formed. There was the Health Research Extension Act in 1985. In the same year, The Guide specifically mentioned the 3Rs. It was around this time that the 3Rs were embraced by industry. Discussions about alternatives became part of corporate culture and for-profit companies began producing in vitro tests. In the 1990s there was a focus on validation and the ECVAM, ICCVAM and the International Conference on Harmonization were established.

The 3Rs Today

Today, before any research group planning to employ animals can begin, their study must be reviewed by an Institutional Animal Care and Use Committee (IACUC), ensuring that the 3Rs are implemented. And replacement has led to many non-animal alternatives. By IACUC standards, researchers must always demonstrate that no alternative exists for animal use in a study. In the spirit of reduction, studies are reviewed thoroughly in order to limit the number of animals used, balancing the needs of a study with the welfare of the animals. And refinement strategies, such as improved housing and handling procedures, ensure that harm or distress is kept to a minimum or eliminated altogether. This improves science in general by minimizing distress and thus making sure data is valid and reproducible.

More than Laws and Regulations

In 1831, British physiologist Marshal Hall proposed five principles to govern experimentation on animals. He stressed observation over experimentation. He emphasized thoughtful consideration of experimental objectives, so as not to repeat investigations. He urged scientists to clearly define their objectives. And of course he stood for the minimization of harm to animals, above all else.

Almost 200 years have passed since Marshall first laid the groundwork for the use of animal models in the scientific process. Over 50 years have passed since Russell and Burch developed the 3Rs. Many regulations and laws have been passed, many organizations established, guidebooks written, and rewritten. But its more than compliance with local laws and regulations, it’s a commitment to the animals, their health and well-being, as they further the knowledge of living systems and contribute to the discovery of life-saving medicines.