The DHS has illegally stuffed America's airports full of $1B worth shitty, malfing facial-recognition tech

Ah. Is there a law requiring a certain process that is required to install security cameras in public places like airports? I wasn’t aware of any such law and was curious which law made it illegal. I’d like to know more about that specific claim as it is a strong one and would likely apply to security cameras in other public areas. Is it a federal or state law? which law? what is the onus? etc.