Say someone signs a lease with someone else. For clarity the drug dealers name will be Mike and other persons name will be Steve. Now Mike begins to drug deal and do drugs inside the house along with breaking a bunch of other laws. Steve sees this for a while and does nothing. Until one day Mike steals something from Steve. Now Steve would like to see Mike arrested and jailed for drug dealing, possession of drugs, and crimes he has confessed to Steve. Evidence would be in Mike's room and Text messages that Mike has on his phone would confirm the truth about the crimes he has confessed to.
If Steve were to call the police (and he is on the lease) could he have them walk in to the house and go into Mike's room to find the evidence of these crimes (without Mike's Permission) and arrest him on the spot? Also Mike would have no criminal record in this hypothetical scenario.