The concept of justice toward animals has evolved from philosophical discussions to matters of legal and ethical importance. Over time—from Ancient Greek philosophy, through the Middle Ages, the Scientific Revolution, the Age of Enlightenment, and into the twentieth century—there have been developments such as animal welfare legislation, scientific advancements in humane standards, and expanding advocacy efforts. In the twenty-first century, there has been broader recognition of animal sentience, the introduction of stronger legal protections, and ongoing debates related to factory farming, animal testing, and veganism, reflecting changes in approaches to animal justice.