10 Things You Learn Re-Watching Watchmen Episode 1
7. The New Masks Aren't Vigilantes
A lot of online articles and discussions refer to Sister Night, Looking Glass, and the rest of the gang as vigilantes and heroes. On a rewatch, the show makes it quite clear that these characters are just the alternate universe equivalent of "plainclothes detectives".
They aren't in uniform, but they are very much police, subject to the same laws as the other boys in blue. All of the named masked characters were wearing their official police badges throughout their work.
This is a clever mirror image of the masked characters of the original work, who began as independent vigilantes and were gradually woven into the apparatus of the law... or exiled entirely.
It's equally important to recognize the misconduct of the masked detectives, who break, enter, and subsequently kidnap a suspect without a warrant. Sister Night beats the suspect pretty senseless without any legal backing on at least two occasions. These masked characters aren't literally vigilantes, but they are acting like them.