Generally, if an individual is going to be searched by a police officer, the police needs a search warrant to search in places where the person has a “reasonable expectation of privacy” (such as in their home, bedroom, or living quarters). However, the police can still search such areas without a warrant if an individual willingly gives their consent to such a search.

However, the question of whether a 3rd-party can consent on behalf of another is more difficult to ascertain. Generally speaking, 3rd-party consent searches may be legal if:

• The area being searched is shared in common with the person under suspicion AND the 3rd  party (such as a common living area, a common dining room, hallways, shared bathrooms, etc.);
• The 3rd party legally has to possess some actual control over the shared area (i.e. they have a key to various areas on the premises, and/or items such as areas or their name is listed jointly on a lease);
• The consent is offered by the 3rd party willingly and without and coercion or deceit by a police officer;

Also, courts usually treat police searches of private areas on an individualized basis. For instance, if the search was being conducted in the suspect’s closet, which they always kept locked and indicated as “off-grounds” to even their roommate, then the roommate might not be authorized to consent to a search of that area. Again, this all depends on the individual factors of each case.