Brothel Law- Myth or Mandate?

[Jimmy O'Connor]

I'm always looking for creative ways to MAKE a deal (you can exhale, I'm not looking to make a brothel) rather than hoping a deal falls into my lap. I've been working on a property which zoning only allows a duplex by right, however, the square footage is twice the size of most duplexes in this pocket. I was looking to pivot to renting by the room and take away excess living space in favor of more "units" (for lack of a better term) when an investor brought up the potential of running into "brothel laws" which are most commonly spoken in reference sorority houses and with x-amount of unrelated women living together to fall into this classification. 

Are brothel laws a real thing? Has anyone ever tried to rent by the room and run into this ridiculous red tape? AGAIN- not trying to make a brothel.