What is Consent?
If consent is given by a person reasonably believed by an officer to have authority to give such consent, no warrant is required for a search or seizure. So, if a suspect’s "significant other" provides police with a key to the suspect’s apartment, and police reasonably believe that she lives there, the search will not violate suspect’s Fourth Amendment rights even if she did not live there and even if she, in fact, lacked authority to consent. See Illinois v. Rodriguez, 497 U.S. 177 (1990).
EXAMPLE: Officer Warren knocks on a murder suspect’s door. the door is answered by the suspect’s 6 year old child, Timmy. The officer asks Timmy “Is it okay if I come in and talk to your Dad? He’s expecting me.” And then walks into the apartment. He then sees the suspect, Roland, sitting on the sofa oiling his illegal Tommy-gun, the suspected murder weapon. He arrests Roland for possession of the gun and seizes the evidence. Because Timmy, being a small child, was not legally able or authorized to give consent, the entry was illegal and the evidence will be excluded.