This Act prohibits the creation and transfer of specific human-animal chimeras, including those with human brain tissue or reproductive cells, while exempting certain research involving human genes or transplants.
Christopher "Chris" Smith
Representative
NJ-4
The Human-Animal Chimera Prohibition Act of 2025 establishes federal criminal penalties for knowingly creating, transferring, or possessing specific types of human-animal chimeras, including embryos mixing human and nonhuman cells or animals engineered to develop human-like brains or reproductive cells. This legislation broadly bans the mixing of human and nonhuman life forms in defined ways, while explicitly excluding certain research involving the transplantation of human cells or the addition of human genes to animal models. Violations of this Act could result in up to ten years in prison and significant fines.
Federal Bill Bans Human-Animal Chimeras: Creation Now Carries 10 Years in Prison and $1M Fine
The “Human-Animal Chimera Prohibition Act of 2025” is adding a brand new chapter to federal criminal law, specifically banning the creation, transport, or even the attempt to create certain types of organisms that mix human and nonhuman cells. This isn’t about stopping Frankenstein’s monster; it’s about drawing a very sharp, federally enforced line in the sand for biological research.
The Line in the Lab: What's Now Illegal
This bill makes it a federal crime to knowingly create or deal with a laundry list of “prohibited human-animal chimeras” (SEC. 2). The definition is broad and covers several complex scenarios. For example, it bans creating an embryo by fertilizing a human egg with nonhuman sperm (or vice versa), or mixing human and nonhuman cells in a way that makes the resulting organism capable of developing human reproductive cells. It also bans transferring a human embryo into an animal womb, or an animal embryo into a human womb. The penalties are serious: up to 10 years in federal prison, fines, or both. If you profit from the illegal activity, the civil fine is the greater of $1 million or twice your gross gain.
Brains, Faces, and the Chilling Effect
Two of the most specific prohibitions are the ones that could have the biggest impact on advanced biomedical research. The bill bans engineering a nonhuman animal to grow a brain that is “mostly or entirely made of human brain tissue” or engineering a nonhuman animal to have “human-like facial features” (SEC. 2). While this addresses clear ethical concerns about creating creatures with human-level consciousness or appearance, the language is vague enough to cause real headaches for researchers. What exactly qualifies as “human-like facial features”? And who decides the percentage threshold for “mostly human brain tissue”? For scientists working on complex neurological diseases using animal models, this vagueness, coupled with the threat of a 10-year prison sentence, could create a significant chilling effect, potentially stifling research that doesn't intend to cross these ethical boundaries but might accidentally brush up against them.
The Research Carve-Out
It’s important to note what this bill does not ban. It explicitly carves out exceptions, stating it does not prohibit using animal models that have human genes added to them, nor does it stop the transplantation of human organs, tissues, or cells into animals (SEC. 2). This means that common medical research practices—like putting human tumor cells into a mouse to study cancer, or using animals to grow human organs for transplant (xenotransplantation)—are still allowed, provided they don't involve the specific prohibited actions, like creating human reproductive cells inside the animal or developing a predominantly human brain. The bill attempts to thread a needle: banning the creation of organisms that blur the line of personhood while allowing research that uses animals as biological tools.