Increasingly police in the United States have resorted to "locking down" buildings, blocks and even entire neighborhoods. For example, recently police in Baltimore reacted to a cop getting shot by locking down an entire section of city. Presumably the only test of such actions would be for someone to get arrested for violating the "lockdown".

On their face, these actions seem to be extra-judicial since in many cases the police are not acting under the penumbra of law, but are essentially creating martial law with no authority.

Another issue is that such actions could be construed as violating the First Ammendment's guarantee of the right of assembly. A long essay on a Constitutional law web site discussed some of the issues with regards to curfews.

Have these police lockdowns been challenged in court or been declared unconsitutional by a court?

  • The essay you cite discusses juvenile curfews only, and I am not sure it is directly relevant. I think there is an important distinction between a standing curfew ordinance, and a temporary restriction for the (ostensible) purpose of immediate public safety in response to an emergency, and/or the investigation of a particular crime. Nov 16, 2017 at 20:03
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    Also, I think the reference to "martial law" is unhelpful. For one thing, martial law is by definition imposed by military authorities, whereas the restrictions you describe are certainly being imposed by civil authorities. What you describe may or may not be legal, and maybe you think it is similar in some ways to what might be imposed by martial law, but I don't think the comparison is going to be relevant to a legal analysis. Nov 16, 2017 at 20:07
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    One more question: on what basis do you assert that "the police are not acting under the penumbra of law"? What research have you done to convince yourself that no legal authority exists for such restrictions? It might help people avoid going over the same ground needlessly. Nov 16, 2017 at 20:15

1 Answer 1


This speaks specifically to roadblocks, as I am unsure about such "lockdowns," especially when considered in various contexts such as active shooters, terror attacks, etc.

Police usually need at least reasonable suspicion that a law has been violated in order to pull a driver over. However, the Supreme Court has recognized that sometimes there are special law enforcement needs. When those needs are present, the Supreme Court has approved of police setting up roadblocks to stop drivers without the police having any suspicion that that drive had violated a law.

There are two things that must be true for any given roadblock to be deemed appropriate. First, it must stop vehicles on a neutral, articulable standard. (An example is: "all cars"). Second, the roadblock must be designed to serve the police officers' efforts closely related to a particular problem regarding vehicles and their mobility.

A roadblock to test for drunk drivers: valid due to the extent of the problem of drunk drivers.

A roadblock to search cars for illegal drugs: invalid because its only purpose is to detect evidence of a regular crime (in other words, it has nothing to do with driving).

Addendum to address fixed checkpoints based on comment:

I came back to this and wanted to expand on the fixed checkpoints, which are checkpoints run by the border patrol inside of the US border. Crossing the checkpoint, a vehicles slow down and officials peer inside. Vehicles may or may not be asked to stop.

Border officials may operate such checkpoints in order to look inside of crossing vehicles and they may do so without a reasonable suspicion that the car includes illegal aliens. They also do not have to be approved in advance, so there is no prior evidence-gathering needed to put one up. Further, officials can point a car to a secondary pull-off location for limited inquiry, also without a reasonable suspicion. It does not require the higher standard because the nature of the secondary pull-off search is not as intrusive as that of a roving stop (where the official is part of a roving patrol and may stop vehicles but does require a reasonable suspicion.). This decision was justified because of the fact that the nature of smuggling makes finding a "reasonable suspicion" standard impractical while not being a great intrusion on Fourth Amendment rights.

  • Border patrol checkpoints have nothing to do with driving, yet are allowed. Also, you're confusing the situation in the article (no people allowed to pass, to which the term "roadblock" seems better suited) with a law enforcement checkpoint (which may be called a roadblock but arguably isn't). In the latter case, which you discuss, people can pass after satisfying certain criteria, while in the article cited in the question, nobody is allowed in or out of a certain area.
    – phoog
    Nov 16, 2017 at 20:09
  • Borders are not relevant here. First, because vehicles are key (albeit not necessary, but necessary isn't the requirement) to the smuggling across borders. Thus the checkpoint obviously is designed to serve the officers' purposes re: a particular problem re: vehicles and their mobility. Of course, the first element is met, too. However, the right to international travel has not been declared to be fundamental. It may be protected from arbitrary federal interference and Due Process Clause protects it in some situations. See Haig v. Agee 453 US 280 (1981); Regan v. Wald 468 US 222 (1984)
    – A.fm.
    Nov 16, 2017 at 20:26
  • Fair point on the distinction between the roadblock and the checkpoint. Most likely it is the same analysis, though. And with respect to the freedom of assembly argument, one would have to show the police were trying to stop the assembly from taking place due to objections to its message.
    – A.fm.
    Nov 16, 2017 at 20:27
  • I'm not talking about borders, I'm talking about Border Patrol checkpoints, which do not occur at borders. See en.wikipedia.org/wiki/… and US v Martinez Fuerte. I don't think the Martinez Fuerte decision depended on any finding that anything was "closely related to a particular problem regarding vehicles and their mobility."
    – phoog
    Nov 16, 2017 at 21:22
  • Added addendum. The checkpoints have an even lower standard to stop and search.
    – A.fm.
    Nov 18, 2017 at 10:52

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