[1] The organization works largely through state-by-state litigation in what it determines to be the most appropriate common law jurisdictions and bases its arguments on existing scientific evidence concerning self-awareness and autonomy in nonhuman animals.

[2] In late 2014, NhRP President Steven Wise and Executive Director Natalie Prosin announced in the Global Journal of Animal Law that the Nonhuman Rights Project was expanding its work into other countries, beginning in Switzerland, Argentina, England, Spain, Portugal, and Australia.

Commenting on the importance of the Somerset case to the NhRP in a 2014 article by Charles Siebert in The New York Times Magazine, Wise said: A legal person is not synonymous with a human being.

In an interview with James Gorman of The New York Times following the organization's first lawsuits, Cupp said, "The courts would have to dramatically expand existing common law for the cases to succeed.

[19][20] On March 19, 2015, the case of Hercules and Leo was refiled,[21] and on April 20, 2015, Justice Barbara Jaffe issued an Order to Show Cause and Writ of Habeas Corpus.

[22][23] Because the order's title included the phrase "WRIT OF HABEAS CORPUS" it made headlines around the world and was misinterpreted as granting the right to liberty to a chimpanzee.

NhRP argued that the fact that a chimpanzee is not a human being should not prevent the argument that it is a legal person with a habeas corpus right to liberty.

[12][33] It then made its central point, that based on previous common law decisions such as Somerset v Stewart, autonomy and self-determination are the human qualities that are intended to be protected by the writ of habeas corpus.

NhRP argued that a chimpanzee possesses qualities such as: the possession of an autobiographical self, episodic memory, self-determination, self-consciousness, self-knowing, self-agency, referential and intentional communication, empathy, a working memory, language, metacognition, numerosity, and material, social and symbolic culture, their ability to plan, engage in mental time travel, intentional action, sequential learning, mediational learning, mental state modeling, visual perspective-taking, cross-modal perception, their ability to understand cause-and-effect, the experiences of others, to imagine, imitate, engage in deferred imitation, emulate, to innovate and to make and use tools.

Ralph A. Boniello III, also held a hearing, denying the NhRP's petition on the grounds that Kiko is not a person for purposes of habeas corpus and stating that he did not want to be the first "to make that leap of faith.

W. Gerard Asher, did not hold a hearing, writing in a decision that he was denying the petition for habeas corpus on the basis that chimpanzees are not considered legal persons.

It further reasoned that in accordance with the social contract one's rights cannot come without obligations: The lack of precedent for treating animals as persons for habeas corpus purposes does not, however, end the inquiry, as the writ has over time gained increasing use given its great flexibility and vague scope.

Reciprocity between rights and responsibilities stems from principles of social contract, which inspired the ideals of freedom and democracy at the core of our system of government.

[37] Like Tommy's, Kiko's appeal was also granted and oral argument took place on December 2, 2014 before the New York Supreme Court Appellate Division, Fourth Department in Rochester, NY.

When asked which one of those grounds is most similar to the circumstances of this petition, NhRP replied that a chimpanzee is more akin to a child near the age of five rather than a mentally disabled adult.

(The NhRP is demanding that Kiko be moved from his solitary caged confinement to the spacious sanctuary of Save the Chimps in Fort Pierce, Florida, where he will live his life on a semi-tropical island surrounded by dozens of other chimpanzees.)

[24][25] "Justice Recognizes Two Chimpanzees as Legal Persons, Grants them Writ of Habeas Corpus" was the headline of NhRP's breaking news post on its website.

[23] The next day NhRP updated its posting stating that "the Order does not necessarily mean that the Court has declared that the two chimpanzees, Hercules and Leo, are legal persons for the purpose of an Article 70 common law writ of habeas corpus proceeding.

In his posting titled "That's One Small Step for a Judge, One Giant Leap for the Nonhuman Rights Project", Wise emphasized the fact that Justice Jaffe agreed with NhRP when finding that "'persons' are not restricted to human beings, and that who is a 'person' is not a question of biology, but of public policy and principle.

"[30] He finished by quoting the last paragraph of Justice Jaffe's decision: Efforts to extend legal rights to chimpanzees are thus understandable; some day they may even succeed.

Courts, however, are slow to embrace change, and occasionally seem reluctant to engage in bolder, more inclusive interpretations of the law, if only to the modest extent of affording them greater consideration.

As Justice Kennedy aptly observed in Lawrence v. Texas (the 2003 gay rights case that struck down a state sodomy statute), albeit in a different context, "times can blind us to certain truths and later generations can see that laws once though necessary and proper in fact serve only to oppress.

[55] An appeal was filed in August 2015, however that December Stony Brook transferred the chimpanzees back the New Iberia Research Center, ending the case, since the New York State Court no longer had jurisdiction over them.

[57] Happy was the first Asian elephant to pass a mirror test, commonly used by scientists to gauge self-awareness through an animal’s ability to recognize itself back in 2005.

[59] In 2018, the NhRP brought a petition for a writ of habeas corpus on Happy’s behalf, seeking recognition of her fundamental right to bodily liberty and transfer to an elephant sanctuary.

The Court of Appeals agreed to hear arguments regarding whether Happy, an elephant and an autonomous nonhuman animal should be released pursuant to habeas corpus.

[63] "The claim that an orca is enslaved within the meaning of the Thirteenth Amendment is unlikely even to receive a single vote from a federal appellate court in 2011," Wise wrote on the NhRP's website.

Richard Miller, granted permission to the NhRP to appear in the case as an amicus curiae (or Friend of the Court) to, as Wise said, "ensure that the orcas' best interests are being properly represented, that their legal status is advanced, and that an unfavorable ruling inflicts the least possible harm on the development of an animal rights jurisprudence.

Pennebaker and Chris Hegedus announced in July 2012 that their next project, Unlocking the Cage, would follow the NhRP's efforts to achieve legal rights for nonhuman animals.

[69] In April 2014, Pennebaker-Hegedus Films released a preview of the as-yet-unfinished documentary in the form of a New York Times Op-Doc called Animals Are Persons Too.