Article: Notice if the mirror seems to be hanging on the wall or if it's part of the wall itself. If it appears to be hanging, try to look behind it and see a wall. If the mirror seems to be part of the wall itself, there's a good chance it's a two-way mirror, which must be set into the wall rather than hung onto it. That way, people standing on the other side of the wall can observe someone looking in the mirror.  A two-way mirror is a piece of glass coated with a substance called micro pane. If you stand on the treated side, you see your reflection but the untreated side looks like a tinted window. If you see a wall behind the mirror, it's a good bet that it's nothing more than a regular mirror. Look around and determine whether the lighting seems extraordinarily bright. If so, you might be looking at a two-way mirror. However, if the light in the room is relatively dim, and you can't immediately see through the mirror, it's probably just a standard mirror. For a two-way mirror to be effective, the light on the mirrored side needs to be 10 times brighter than the light on the other side. If the lighting is any dimmer, it's possible to see through the glass to the observation area. If you're in a public place and in an area where you'd expect privacy, such as a restroom, it's unlikely and illegal to have a two-way mirror. On the other hand, two-way mirrors are frequently used by law enforcement. For example, two-way mirrors are used in interrogation rooms and for lineups.  The use of two-way mirrors is closely tied to issues of personal privacy and Constitutional rights. Most states have passed additional legislation preventing the use of two-way mirrors in rest rooms, locker rooms, showers, fitting rooms and hotel rooms. If a location has chosen to use two-way mirrors for surveillance, they are required to post signs that notify you.  Many places, such as gas stations, will use one way metal mirrors because glass mirrors can be destroyed by users. If the mirror in question is metal, then it is not a two-way mirror.
What is a summary of what this article is about?
Observe how the mirror is installed. Check out the lighting. Consider where you are.