A paparazzo whose schtick is to work topless is suing the NYPD -- claiming cops had NO RIGHT to arrest her for going boobs-out in public ... because half-naked is LEGAL in NYC.
TMZ has obtained a lawsuit filed by 46-year-old Holly Van Voast -- who regularly prowls the streets of NYC -- sans top -- in search of celebs to photograph and interview.
In the suit, H.V.V. claims ... since 2011, she's been arrested or detained AT LEAST 10 TIMES for being topless in public.
In fact, Holly claims she's even been dragged off to psych wards and lectured by cops in an effort to deter her from flashing her cans where she damn well pleases.
Problem is, Holly claims her topless hobby is legally protected in NYC, and cites a 1992 ruling by the New York appeals court which states it is NOT illegal for women to expose their breasts in a public park.
In her suit, Holly also points to a memo issued by the NYPD in February which states NO ENFORCEMENT ACTION is to be taken against any person -- male or female -- for waist-up exposure.
But there's more ... in the suit, Holly explains the topless gimmick is partially to gain exposure for her friends in the "punk drag" community ... and she even names some of her favorite "punk" drag queens -- Charmin Ultra, Misty Meaner, Mary Jo Cameltoe, Heidi Glum and Cherry Poppins.
Holly is suing for false imprisonment, among other things ... and wants unspecified damages.
We called the cops for comment -- so far, no word back.