Those through-the-wall sensors police and federal agents have been using for years in secret? Like drones and other surveillance technologies, they migrated back to the United States from the wars in Iraq and Afghanistan.

It's not an exaggeration to say that people concerned about police practices and the Fourth Amendment in the United States should pay close attention to the tactics and technologies deployed overseas by US warfighters. Those tactics and technologies eventually end up being used against Americans here at home—too often in secret, with zero outside accountability, and in ways that potentially violate the constitution.

The militarization of the police is not a figurative statement. I guess that means we can look forward to these things patrolling our neighborhoods in future decades:

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