When New Zealand's parliament passed the Animal Welfare Act 1999 which banned the use of non-human hominids in research, testing, and teaching except where such uses are in the hominids' best interests. New Zealand became a world leader in great ape protection. The first part of this paper briefly examines the history, major features, animal welfare code, enforcement and penalties of the Act. It analyzes, thereafter, relevant provisions relating to great ape. Part III of this article discusses the Great Ape Project, explaining a United Nations Declaration of the Rights of Great Apes and practices of major countries. As is well known, all members of the Homindae Family, such as humans, chimpanzees, bonobos, gorillas, and orangutans, share complex cognitive aptitudes. However, only humans have legal rights to life and personal security. And also great apes have been classified as endangered species due to deforestation, hunting and wars etc. Under these circumstances, the book titled "Great Ape Project" was published by 34 authors, in 1993. The authors argues that humans are intelligent animal with social, emotional, and cognitive life. If great apes also display such attribues, they deserve the same consideration humans extend to members of their own species. In the same year, an international organization of the same name was established by primatologists, anthropologists, ethicists, and other experts who advocate a United Nations Declaration of the Rights of Great Apes that would confer basic legal rights on non-human great apes. The Great Project ultimately seeks full moral and legal personhood for great apes. This paper explores, thereafter, the reasoning behind the United States Court of Appeals for the District of Columbia's decision in Animal Legal Defense Fund, Inc.(ALDF) v. Glickman which is a landmark decision for promoting humane treatment for animals. It attempts to analyzes, in particular, the standing requirements which are injury in fact, causation, redressability and zone of interests. In the last part of this paper, it proposes several solutions for protecting fundamental interests of animals, particularly great apes such as granting legal standing to great ape, introduction of a guardian system and a private right of action provisions etc. The most desirable solution would be to permit plaintiffs, such as animal welfare organizations and individuals meeting the standing requirements, to represent animals and assert claims on behalf before a court. It is expected that the proposals mentioned above can be actualized in the near future through the efforts of animal welfare organizations, individuals, the judiciary and Congress.