Justice may not require that animals be exactly the same as humans or that they have rights exactly coterminous with the rights of humans, but justice would require that animals receive protection in ways that match up with those similarities they share with humans that are characteristics considered essential to the understanding of what it means to be human. Stated generally, the argument is that if animals are similar to humans as to capacities and characteristics of humans that define humans, then animals should receive protections equivalent to the protections of humans because a just society treats like entities alike.
Taimie L. Bryant,
Similarity or Difference as a Basis for Justice: Must Animals Be Like Humans to Be Legally Protected from Humans?,
70 Law and Contemporary Problems
Available at: http://scholarship.law.duke.edu/lcp/vol70/iss1/8