Can a police officer enter a person's home, enter the front door and speak to him?

In Titemore, a police officer wishing to speak with a suspect in his home walked across the front lawn, up three steps to a porch, and approached a sliding-glass door. 437 F.3d at 254, 259. The glass door was open, but the screen was closed. Standing outside the screen door, the officer spoke to Titemore, who was sitting in the room with a firearm nearby. Id. The district court denied Titemore's motion to suppress the eventual seizure of the gun as the fruit of an unlawful entry onto his property, holding that an officer does not offend the Fourth Amendment when he approaches any part of a building where uninvited visitors could be expected. United States v. Titemore, 335 F.Supp.2d 502, 506 (D.Vt.2004).