As one of humans’ most significant institutions, legal systems have impacted greatly the ways in which humans deal with other living beings. There are several different kinds of legal systems around the world, and while most of the discussion here focuses on the legal tradition known generally as the common law tradition, the general principles discussed also apply to other major legal traditions such as the civil law traditions, Islamic law, and indigenous legal traditions.
The style of legal system that has come to be known as “common law” originated in England. It is an approach to law making that gives great deference to custom and general principles as they are embodied in cases decided by judges—these cases serve as precedent and are applied to situations not covered by laws that a legislature has passed. Common law systems are found in a wide range of countries, including Australia, Brunei, Canada, Ghana, Hong Kong, India, Ireland, Kenya, Malaysia, New Zealand, Pakistan, Singapore, South Africa, Sri Lanka, Tanzania, and the United States.
The common law tradition has been a pioneer in the use of “rights” as a legal way of thinking. Since legal systems are the place where legal rights are worked out, discussions about animal rights, whether of the moral or legal sort, go much better when the status of nonhumans under law is clearly understood. It is also important to recognize that today there is