The Food and Drug Administration announced Monday that it is updating federal regulations to make clear that drug developers can use alternatives to animal testing before medicines are tested in humans.
There is just one wrinkle.
Congress changed the underlying law nearly four years ago.
The FDA’s new direct final rule replaces regulatory references to “animal tests” and “animal studies” with broader terms such as “nonclinical tests” and “nonclinical studies.” It also removes language that the agency says could suggest animal testing is the only acceptable method for producing safety information.
The change opens the regulatory vocabulary to technologies that sound considerably more 2026 than the rules they are replacing. Those include human-cell systems, organs-on-chips, computer modeling and other New Approach Methodologies, commonly known as NAMs.
But the FDA is not suddenly abandoning animal testing. And drug companies did not wake up Monday with an authority Congress had never given them.
The statutory change dates to 2022.
Congress Got There First
The Food and Drug Omnibus Reform Act of 2022, enacted as part of the Consolidated Appropriations Act for fiscal year 2023, amended federal drug law to replace references to animal testing with the broader concept of “nonclinical tests.”
Congress also defined what that meant.
The law recognized testing conducted in vitro, in silico, in chemico and through nonhuman in vivo methods. In plain English, the statutory framework could encompass laboratory testing involving cells, computer-based modeling, chemical testing and traditional animal studies.
Animal testing remained an option. It simply stopped being the only category written into the statute.
FDA’s regulations, however, continued using older terminology.
Now, in September 2026, the agency is cleaning that up.
According to the FDA, the new rule brings its regulations into alignment with the 2022 law and removes wording that could leave developers with the impression that animal studies were the required path for generating certain safety evidence.
That distinction matters.
The FDA explicitly says the rule does not prohibit animal studies, reduce existing evidentiary standards or impose new requirements or costs on drug developers. Instead, it clarifies that validated non-animal methods can be used when appropriate for the particular drug and regulatory question.
In other words, this is less an abolition of animal testing than a regulatory vocabulary lesson four years in the making.
Why the Words Matter
Changing terminology in the Code of Federal Regulations can sound like the sort of administrative housekeeping best enjoyed with a strong cup of coffee.
But in this case, the words can have practical consequences.
Drug developers deciding how to design expensive safety studies do so within an elaborate regulatory system. If the statute says one thing while the implementing regulations continue referring specifically to animal studies, uncertainty can influence how sponsors design those studies and what evidence they believe FDA expects to see.
FDA itself acknowledges the problem.
The agency says clearer terminology and regulatory expectations can reduce avoidable uncertainty for sponsors preparing the evidence needed to begin human clinical trials.
That raises an obvious question.
If Congress broadened the statutory framework in 2022, what happened during the years in which FDA regulations continued using terminology the agency now says could suggest animal testing was the only acceptable approach?
The answer will require more than Monday’s press release.
FDA Provides 25 Places to Start Looking
Alongside the rule, FDA launched a database containing 25 examples of New Approach Methodologies already found in publicly available agency review materials.
That may ultimately prove more interesting than the terminology change itself.
The examples provide a starting point for examining how drug developers have actually used alternative testing methods and how FDA reviewers treated that evidence.
It also provides a way to begin measuring the transition rather than simply announcing one.
Which companies used NAMs? What methods did they use? Were animal studies reduced or replaced? How did FDA evaluate the alternative evidence? And how frequently were these approaches being used while the agency’s regulations still contained the older language?
Those are questions worth following.
The Rule Is Not Quite Final Yet
There is another bit of regulatory machinery still running.
FDA published the change as a direct final rule while simultaneously issuing a companion proposed rule and opening a public-comment period.
If the agency receives significant adverse comments, it says it will withdraw the direct final rule and proceed through the traditional notice-and-comment rulemaking process using the companion proposal.
If that does not happen, the updated terminology can move forward without another full round of rulemaking.
Either way, the direction is clear.
Congress changed federal law in 2022 to recognize that the evidence supporting human drug trials does not necessarily have to come from animal studies. Technology continued advancing. Drug developers began using newer methodologies. FDA has now assembled examples showing those methods in practice.
And in 2026, the regulations are finally getting new vocabulary to match.
For a regulatory system preparing to embrace organs-on-chips and sophisticated computer models, apparently one of the first modernization projects was updating the nouns.
