Non-animal tests are allowed – now we must make them compulsory
The U.S. is moving toward a future where animal testing is no longer the default – but more needs to be done to make that future a reality.
The 2022 FDA Modernization Act 2.0 removed an 84-year-old requirement that new drugs are tested on animals as part of their development. The law replaced the requirement for ‘preclinical tests (including tests on animals)’ with the broader term ‘nonclinical tests’, opening the door to the use of scientifically justified non-animal approaches.
Now, the FDA Modernization Act 3.0 would build on its 2.0 predecessor to direct the FDA to bring its regulations in line with the changes made by the 2022 law. The new legislation was approved by the House of Representatives in July, after the Senate had unanimously passed its companion bill, and now awaits a vote in the Senate before it can be sent to the President.
These are positive changes. Removing requirements for animal testing, and making it easier to use non-animal methods, are important steps towards modernizing safety testing. However, neither Act stipulates that an available non-animal method must be used instead of an animal test.
This is an important distinction. The fact that a non-animal method exists and is allowed to be used does not mean that it WILL be used, or that the animal test will stop. Animal tests often continue for years after suitable non-animal methods become available.
This can happen for many reasons, including unclear regulatory requirements, uncertainty about whether regulators will accept a newer method, reluctance to move away from established practices, lack of international harmonization, and the continued inclusion of animal tests in regulations and guidelines.
We are continuing our work to break down these barriers and make real replacement a reality. This includes seeking clearer regulatory guidance on the use of non-animal methods. In July, we submitted detailed comments on the FDA’s draft guidance on streamlined safety studies for certain cancer drugs. The guidance recognizes that, in some circumstances, drug developers can reduce or replace animal studies by relying on existing evidence and other scientifically justified approaches.
We welcomed this progress but encouraged the FDA to go further, asking them to make it clear that reliable non-animal methods should be considered from the outset and routinely incorporated into safety assessments wherever they can provide the information needed to protect patients.
Guidance alone, though, is not enough. We are also asking for stronger legislation. The Replace Animal Tests Act (H.R. 6660) would build on the progress made by the FDA Modernization Acts, by moving from simply allowing non-animal methods to requiring their use when they can replace an animal test. Entities regulated by federal agencies, including the FDA, would have to use a scientifically appropriate non-animal method instead of an animal test whenever it can meet regulatory requirements.
The Replace Act would also require agencies to identify approved non-animal methods and clarify which animal tests they can replace, whilst increasing transparency through annual agency reports on the number of animals used in testing and the use of non-animal methods.
Together, these efforts can help move the U.S. from simply allowing non-animal methods to ensuring they are actually used to replace animal tests.
We will continue working with lawmakers, regulators, and scientists to ensure that advances in human-relevant science translate into real reductions in animal testing.
You can help
If you live in the United States, you can help modernize testing across federal agencies.
Ask your Representative to support the Replace Animal Tests Act (H.R. 6660) and help make sure that when a reliable non-animal method is available, animals are not subjected to an outdated test simply because it has always been done that way.
Published on 14 August, 2026.
