If the police want to search a house for drugs or other evidence of criminal activity, there are two primary ways they can do that. One, depending on how the the property is situated, the police can usually walk up to the front door, knock and ask to search the residence if someone answers the door. If the person who answers the door has apparently authority to give the police permission to search the residence, and does so, then the police can search the residence. Two, if the police have specific evidence that there are drugs or other evidence of criminal activity in the house, they can apply to a judge for a search warrant. If the judge signs the search warrant, the police can use that search warrant to search the residence.
Even where there is a search warrant, a criminal defense lawyer can still challenge the search in the subsequent criminal case. Search warrants are difficult to overcome in criminal cases because the criminal defense attorney is basically asking a judge to rule that the initial judge who signed the search warrant made a mistake. Judges do not like to do that. Even worse, the second judge already knows drugs or other criminal evidence were found in the house, otherwise there would not be a criminal case in which to file the motion to suppress.
But, every now and then, a criminal defense lawyer can successfully challenge a search warrant. In a recent case near Jacksonville, Florida, the police received an anonymous tip that the suspect was making and selling methamphetamine in his house. Normally, the police will then take steps to try and corroborate the tip- conduct surveillance outside the house, knock on the door and see if they can detect an odor or get someone to answer questions, check the trash on the side of the road and other law enforcement techniques. In this case, the police did some surveillance but did not see anything indicating there was drug activity at the house. They also checked the criminal histories of the occupants of the house and noted they had prior drug convictions. Based on this, the police went to a judge, got a search warrant, searched the house and found methamphetamine and drug paraphernalia inside.
The criminal defense lawyer filed a motion to suppress and argued that there was not sufficient evidence of drug activity to justify a search warrant for the house. The criminal judge ruled against the criminal defense attorney, as they often do in these circumstances, but the defendant won the argument on appeal. An anonymous tip about drug activity is not very reliable and cannot be the basis for a search warrant. Anyone can say anything about anyone else for whatever reason, and if the person will not identify him/herself, that tip is less credible. Beyond that, there is nothing illegal about having a criminal record. The police needed to present some specific evidence that the defendant was engaged in criminal activity in his house. Had the police searched his trash and found materials used to make methamphetamine, that would have corroborated the tip and likely been sufficient for a search warrant. Since they did not do that, the drug evidence obtained during the search was ultimately thrown out.