Legally: This depends on the type of surveillance. Reading someone's first class mail requires a warrant. Posting a car on public streets to observe them requir

Legally: This depends on the type of surveillance. Reading someone's first class mail requires a warrant. Posting a car on public streets to observe them requires nothing. Ethically: law enforcement finds most violations of the law in places they look, so if it's unfair where they're looking, it's easy for that to translate into unfair outcomes. A society where police are watching every Capulet but not investigating the Montagues is one where most of the arrests will be of Capulets, regardless of who is actually committing crimes. Therefore, when talking in populations, surveillance approximates punishment and familial surveillance approximates collective punishment of an extended family.