In the United States, police officials can do a variety of searches on your home that are legal despite their location. For example, the police can fly a drone over your house to do surveillance and not violate your rights to privacy. The police can even enter large open fields surrounding your house to legally observe your activity, even if the act of entering that property is legally considered trespassing. But there are limits to what the police can do when it comes to entering your property to conduct a search without a warrant.
Your Front Porch
It is perfectly legal for anyone, strangers or the police, to step onto your property and knock on your front door. The simple act of trying to get your attention by knocking on your door, in most states, is not considered trespassing. However, if a stranger knocks on your front door and does not leave when you ask them to, then that is considered trespassing.
What about the police? What if the police brought their best drug sniffing dog up onto your front porch and then knocked on your door? What would happen if that drug sniffing dog started giving all of its indications that there was something in your house? Without a warrant, there is nothing the police can do.
When the police pull you over in your car or enter your home with a warrant, they can use probable cause to inspect any part of your car or home they consider to be suspicious. For example, if a police officer pulls you over and sees the handle of a pistol sticking out of a jacket on your front seat, they can use probably cause to search your vehicle.
However, that does not apply to your front porch. Unless the police have a search warrant, they cannot use probable cause to enter your home by simply knocking on your front door and standing on your porch.
When Can The Police Search?
If the police knock on your front door and ask to come into your home and you agree to let them in, then the police can use probably cause to search your home and use anything they find against you. The police are also legally allowed to interview you and use anything you say against you when you grant them access to your home.
The police have many different legal weapons they can use to get information from you or search your home. But there are also laws that protect innocent people from the police as well. If a police officer walks up onto your porch and wants to interview you or enter your home, you have the legal right to deny their request and ask them to leave. However, if you get violent in your insistence that the police leave your property, then you have given up your rights and could be arrested on the spot.