Can the Police come to my house without a warrant and ask me questions?

Unfortunately, the short answer to this question is yes. As a general rule, a search warrant must be obtained to search an area in which an individual has a reasonable expectation of privacy. However, this general rule is subject many exceptions, i.e., there are several situations in which the police do not need a search warrant.
Tennessee Appellate Courts have crafted an exception to search warrant requirement known as a “knock and talk.” A knock and talk is a law enforcement tactic through which the police knock on people's doors and talk to them about allegations of illegal activity. According to Tennessee Appellate Courts, a knock and talk requires no basis for suspecting crime either has been committed or is in the process of being committed. Police often employ knock and talk tactics when there is not sufficient evidence to obtain a search warrant.
In State v. Cothran, 115 S.W.3d 513 (Tenn.Ct.App.2003), an anonymous caller informed the police that methamphetamine was being manufactured at a particular residence. The police went to the residence and knocked on the door, after which a male voice shouted “come on in.” Upon entering the residence, the police observed drug paraphernalia in plain view.
The Cothran Court addressed was the legality of the police arriving at a residence and conducting a knock and talk without a search warrant. The Court noted that various federal courts and state courts have recognized knock and talk as an appropriate investigative tactic and that those courts have found that knock and talk is “a consensual encounter, as well as a means to request consent to search a residence.” The Cothran Court drew on the following text from the Ninth Circuit Court of Appeals:

Absent express orders from the person in possession against any possible trespass, there is no rule of private or public conduct which makes it illegal per se, or a condemned invasion of the person’s right of privacy, for anyone openly and peaceably, at high noon, to walk up the steps and knock on the front door of any man’s “castle” with the honest intent of asking questions of the occupant thereof whether the questioner be a pollster, a salesman, or an officer of the law.

The Court concluded that neither probable cause nor reasonable suspicion is needed to conduct a knock and talk.
In reaching this conclusion, the Cothran Court reiterated that a person does not have an expectation of privacy in the area in the front of his residence, which leads from the public way to the front door. Instead, the Court observed that a sidewalk or pathway leading from a public street to the front door of a residence represents an “implied invitation” to the public to use the pathway to interact with those inside the residence. Further, the Court noted that, once the police have conducted a knock and talk, a warrant is not required “when voluntary and knowing consent to enter a residence is given.”
As you can see from the above information, the police can come to your house without a warrant and ask you questions. However, just because the police are at your door does not mean that you have to let them in the home! Remember, the police cannot enter your home without either a search warrant or your permission. If they don’t have a warrant, you have the authority to deny them entry to your home. It’s your constitutional right!
As always, if you are involved with the police and are not sure what to do, tell the police that you want to talk to your lawyer. Usually, nothing good can come from speaking to the police without your lawyer present. Don’t learn this lesson the hard way.