Arguably, you could have a legitimate expectation of privacy (and therefore 4th Amendment rights) in your friend's home. If your friend has voluntarily linked his webcam to the police system, your privacy rights could be violated. Regardless, I wanted to follow up on my earlier post that a private individual likely becomes a government agent for 4th Amendment purposes if he voluntarily links his camera to a police surveillance system. "For a private person to be considered an agent of the government, we look to two critical factors: (1) whether the government knew of and acquiesced in the intrusive conduct, and (2) whether the private actor's purpose was to assist law enforcement efforts rather than to further his own ends." United States v. Simpson, 904 F.2d 607, 610 (11th Cir.1990).