Habeas Corpus for Chimpanzees: Inside the Personhood Cases

Carl Linnaeus once filed the chimpanzee under Homo troglodytes, slotting it into the same genus he reserved for human beings before later naturalists reassigned it to Pan. The taxonomic near-miss has become an unlikely fixture of American legal argument. A nonprofit litigation group has spent several years asking New York courts a question Linnaeus never had to answer: if a chimpanzee shares so much of the human cognitive architecture, can it invoke the ancient writ of habeas corpus to challenge its captivity? So far the courts have said no, but the manner of their refusals is more interesting than the bottom line suggests.

The writ and what it was built to do

Habeas corpus is the procedural mechanism by which a court compels a custodian to justify holding a body. In New York it lives in Article 70 of the Civil Practice Law and Rules, which lets “a person illegally imprisoned or otherwise restrained in his liberty” petition for inquiry into the detention. The statute’s reach has always been generous at the margins: it has been invoked on behalf of infants, the institutionalized, and others who cannot speak for themselves, with a next friend standing in. The threshold question the chimpanzee petitions force is narrower and older than welfare or cruelty law. It is whether the petitioner is the kind of being the writ was ever meant to reach.

That framing draws a deliberate line back to the common-law tradition the petitioners invoke, including the celebrated English ruling that an enslaved man could not be forcibly removed from England against his will. The argument is not that a chimpanzee is a human. It is that the writ protects a legally cognizable interest in bodily liberty, and that the relevant question is whether the being before the court possesses that interest, not whether it belongs to the human species.

Lavery and the duties-and-responsibilities rule

The first appellate answer came in People ex rel. Nonhuman Rights Project, Inc. v. Lavery, decided by the Appellate Division, Third Department, in December 2014. The petition was brought on behalf of Tommy, a chimpanzee kept on private property in Fulton County. The court declined to recognize him as a “person” entitled to the writ, and it grounded that conclusion in a particular theory of legal personhood: that rights and duties are reciprocal, and that an entity incapable of bearing legal responsibilities cannot claim legal rights. Because a chimpanzee, in the court’s view, can neither be held accountable nor shoulder societal obligations, it falls outside the class of rights-bearing persons.

The reasoning is tidy, and it is also vulnerable. The objection that surfaced almost immediately is that the law already extends rights to human beings who cannot bear duties at all: infants, the severely cognitively impaired, the comatose. None of them can be indicted or sued in their own right, yet none would be denied the protection of the writ on that account. If the capacity to bear duties were truly the test of personhood, a large population of indisputable persons would fail it. The court in Lavery did not fully reconcile that asymmetry, and the gap has shadowed the doctrine ever since.

Kiko and the narrower escape hatch

A separate panel, the Fourth Department, disposed of a companion petition on behalf of a chimpanzee named Kiko on a different and more modest ground. In Matter of Nonhuman Rights Project, Inc. v. Presti, the court sidestepped the personhood question and held that habeas corpus does not lie where the petitioner seeks not release from confinement but only a transfer to better conditions. Because the petition sought to move Kiko to a sanctuary rather than to set him free, it asked the writ to do something the writ does not do.

This ground is doctrinally orthodox and, for that reason, harder to dislodge. It says nothing about whether a chimpanzee is a person; it says only that this particular relief is unavailable through this particular writ. The distinction matters strategically. A litigant can answer the conditions objection by pleading for outright liberty, even if “liberty” for a captive-bred chimpanzee realistically means a sanctuary rather than a jungle. The personhood objection, by contrast, goes to the threshold and cannot be pleaded around.

Hercules, Leo, and a judge who took the question seriously

The most searching judicial engagement to date came in the Hercules and Leo litigation, brought on behalf of two chimpanzees then held for biomedical research at a state university. Justice Barbara Jaffe of the New York County Supreme Court initially signed an order to show cause, which some read as a writ granting the chimpanzees standing before any hearing; she later amended it to make clear it was merely an order for the respondents to appear and argue. After full argument she dismissed the petition.

What distinguished the opinion was its candor. Justice Jaffe concluded she was bound by Lavery as controlling appellate authority and could not, as a trial court, declare the chimpanzees persons. But she declined to defend the result as just, and she invoked the language the Supreme Court used in dismantling sodomy prohibitions: that times can blind us to certain truths, and that later generations may see laws once thought necessary as instruments of oppression. The signal was unmistakable. The court was applying the rule it was obliged to apply while inviting a higher court to revisit it.

The comparative and historical backdrop

The New York cases did not arise in a vacuum. Within the same period, an Argentine appellate court referred to a captive orangutan named Sandra as a “subject of rights,” a phrase widely reported as a grant of personhood, though the translated decision and subsequent proceedings were considerably more equivocal than the headlines. The lesson cuts both ways: foreign courts have shown a willingness to loosen the property classification, but the actual legal effect of doing so remains uncertain and contested.

For an American court, the historical resonance is sharper. The petitioners’ reliance on the common-law antislavery tradition is rhetorically potent and legally double-edged. It locates the writ’s purpose in the protection of beings wrongly treated as property, which is precisely the move the chimpanzee cases need. But it also invites the response that the analogy proves too much, sweeping in animals whose legal status the legislature, not the judiciary, has chosen to address through cruelty statutes and welfare regulation. Courts in this line have repeatedly observed that the rejection of a rights paradigm does not leave animals unprotected, pointing to the criminal prohibitions on torture and unjustifiable killing.

Where the doctrine is headed

As of this writing the New York rule is that a chimpanzee is not a “person” within the meaning of the habeas statute, established by intermediate appellate authority and applied, if reluctantly, by the trial courts below. The state’s highest court has not yet squarely resolved the question, and the reasoning of the controlling decisions is unstable enough that it may not survive the next serious confrontation. The duties-and-responsibilities theory in particular looks less like a definition of personhood than a conclusion in search of one.

The likeliest near-term outcome is not a sudden recognition of animal personhood but continued line-drawing: courts distinguishing autonomous great apes from the broader animal kingdom, or legislatures crafting a third status that is neither full personhood nor mere property. Readers tracking how courts handle liberty interests at the edges of the recognized categories may find parallels in the publication’s coverage of contested expansions of search-and-seizure doctrine and in its ongoing case tracker. The Linnaean joke embedded in the slug — that science once filed the chimpanzee under the human genus — turns out to capture the legal puzzle exactly. The animal is close enough to unsettle the categories and far enough away that the courts keep declining to move the line.

This publication offers commentary and analysis on developing law and does not provide legal advice.