This is a question that was raised after watching several TV series on streaming services. It revolves around the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) and activity of USAMRIID on US Soil and whether legally they can be deployed or can act within the United States in the event of a major viral outbreak or other type of situation where they and their scientists are the 'front lines' of a major Biosafety Level 3/4 outbreak domestically.

Origin of the Question

A 1995 movie called "Outbreak" details a fictional viral outbreak of an infinitely lethal pathogen. This pathogen essentially infects an entire town and USAMRIID and US Military are deployed to cordon off the town and act alongside CDC to help identify and then attempt to create an antigen for this fictional pathogen. However, there was a US Army military cordon used in the movie to isolate the affected town.

Two seasons of a series called "The Hot Zone" exist (based on actual real life events, i.e. Ebola Reston and Amerithrax responses and investigations), the first one detailing the Ebola Reston situation where there was an Ebola outbreak in Reston at an animal quarantine place holding monkeys. USAMRIID deployed during that first season to sterilize the facility, neutralize the monkeys, and get samples of Ebola Reston to USAMRIID for study. They operated as a military operation to get in, sterilize the threats, and get out without being seen, however as everyone involved was USAMRIID, they were technically military, so it stands to reason they are not permitted to deploy domestically.

The Question

We know that the Posse Comitatus Act (18 U.S.C. § 1385) limits the ability for the federal government to deploy US military personnel to enforce domestic laws and policies within the US. However, while USAMRIID is a US Military operation out of Fort Detrick, there still seems to be a lot of movies showing USAMRIID deploying in response to domestic biosafety level 3 and level 4 situations, adn then in turn acting in regards to those situations.

I know these movies are dramatizations, and not based in actual US legal cases at times, however I know that USAMRIID along with CDC personnel were involved in eradicating the Ebola Reston 'outbreak' before it spread beyond the quarantine facility.

Does USAMRIID operate outside the Posse Comitatus Act, in that they can coordinate and act on US soil in response to biological threat situations, or are they bound by Posse Comitatus and are not allowed to act to enforce biosafety in the event of outbreaks of BL4 agents like ebola or other filoviruses?

This question is looking for answers based in law and precedent related to Posse Comitatus and whether it affects USAMRIID specific activities states-side in response to biosafety situations. Precedents to support statements are desired in this case.

  • 7
    I think it may hinge on what "execute the laws" means. The standard example is that the military can't arrest people. On the other hand, every federal employee and servicemember is in some sense "executing the law" when they go to work every day, e.g. the laws and regulations calling for the Army to conduct medical research consistent with its mission; this sort of "execution" is surely not forbidden by Posse Comitatus. So the question is, on which side of this line would be something like cleaning up an infectious disease hazard and euthanizing monkeys? Commented Jan 1, 2022 at 23:19

1 Answer 1


The article "The Posse Comitatus Act..." analyzes the legal restrictions on use of military power arising from that act. Following US v. McArthur, 419 F. Supp. 186, where the act played a role in trials related to Wounded Knee, it was found and subsequently supported in various ruling that the

use which is prohibited by the posse comitatus statute is that which is regulatory, proscriptive or compulsory in nature, and causes the citizens to be presently or prospectively subject to regulations, proscriptions, or compulsions imposed by military authority.

Mere "involvement" of "deployment" of the military is not contrary to the act. It should also be noted that the act includes a provision for actions expressly authorized by Congress, as was the case of the Espionage Act of 1917 and the related Magnuson Act of 1950.

Hypothetically (in extremis), Congress might pass a law requiring the seizure of persons infected with a disease. If Congress expressly authorized USAMRIID to effect such seizures, that would not be in violation of the act. Otherwise, it would be. Since USAMRIID is a research lab and not an enforcement arm of the military, it is both highly unlikely that Congress would authorize such activities or that USAMRIID would get involved in this way. W.r.t. their ordinary operations, scientific research, nothing in what they do that contradicts the Posse Comitatus Act.

Since we are dealing in hypotheticals, I should point out that SCOTUS has so far not definitively endorsed the "regulatory, proscriptive or compulsory" test, so that test could be overturned, though it is unlikely to be.

  • 8
    I'll also point to the US Army Corps of Engineers, which is involved in the construction and maintenance of a lot of the US's water infrastructure.
    – nick012000
    Commented Jan 2, 2022 at 12:13
  • So with USAMRIID simply coordinating their resources with CDC in response to a major outbreak (say, if USAMRIID has come up with an antiserum to a specific virus but it's not majorly available because said virus was previously only in high-security BL4 labs and is only just being used and weaponized in a terror attack rather than an act of war), the involvement of USAMRIID and US military 'deploying' research teams and military transports of said antiserums wouldn't be in violation of posse comitatus as it's not a "US Military Enforcement of Domestic Policies" situation? Commented Jan 2, 2022 at 22:45
  • 3
    I believe the last sentence of your penultimate paragraph, “W.r.t. their ordinary operations, scientific research, in what they do that contradicts the Posse Comitatus Act,” is missing the word “nothing” (as in “nothing in what they do”), or similar.
    – KRyan
    Commented Jan 2, 2022 at 23:23
  • @ThomasWard if there is a federal law that calls for USAMRIID to deploy in response to a public health crisis then such deployment is not in violation of 18 USC 1385 because of the "except" clause in 18 USC 1385.
    – phoog
    Commented Jan 3, 2022 at 15:02
  • tl;dr lots of biosafety response isn't law enforcement and the Posse Comitatus Act doesn't apply to the state activated national guard.
    – ohwilleke
    Commented Jan 3, 2022 at 17:40

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