Cops have to have probable cause of an emergency typet to come into your home without a warrant. Like if someone is in danger, but sometimes they tey to pull "we are searching for a suspect". This is not the case and cannot come in. Now if someone is living with you and they give permission then they can cone in without a warrant, even if they are not on the lease. Also to get a warrant its up to whomever is issuing the warrant to determain (most of the time) if the 3rd party (cops) proved reasonable cause and issue a warrant specifying whats to be searched. Things are weird right now. The supreme court just ruled in a case out of SC that if a cop detains you illegally and searches you illegally and finds something to put you in jail its still can be used against you if the cop says what you was doing was illegal, even though it wasnt. "Ignorance is no excuse for the law" that put so many in jail does not apply to leo. The case was about a man pulled over for a tail light out when in SC you are only required to have 1 working. Well they pulled him over for it anyways and searched all his stuff and found alittle coke and arrested him. Court pretty much said that if a cop says you are doing anything illegal, regardless if you was or wasnt, then the 4th doesnt apply to you. Lotta scary stuff right now.