Trespass Theory of Fourth Amendment

by Charles Gillingham

A recent question was posed to the author with this set of facts:

Hundreds of images of child pornography (CP) are being downloaded to multiple Internet Protocol (IP) addresses on one street. It is clear to the officers that at least a few homes have unsecured wireless and someone is downloading CP using their wifi. The question is can the officers use an investigative tool, functionally equivalent to a divining rod, to go on the different properties to determine which residence is actively downloading the images. Is this a problem?

Trespass Theory to Fourth Amendment Jurisprudence

Remember U.S. v. Jones (2012) 565 U.S. 400, the GPS case that found attaching a tracker to suspect's vehicle was a trespass to personal property and thus required a warrant? This case found a new set of police conduct that was violative of the Fourth Amendment. If an officer trespasses in an effort to obtain evidence for a criminal prosecution that evidence is illegally obtained. In this case the act of attaching the tracker was found to be a trespass.

The US Supreme Court expanded the trespass theory to a residence in Florida v. Jardines (2013) 569 U.S. 1. In that case the officers took an investigative tool, a drug sniffing dog, up to the front door of the house to sniff for a marijuana grow. The court held that by taking the dog to the front door to collect evidence the officers trespassed on the property. The court stated that while homeowners generally consent to people approaching their front door, homeowners do not impliedly allow individuals to approach the curtilage of the residence to search for evidence. The court analogized the implied consent an owner gives to a police officer to approach to a front door of a residence to that of a trick-or-treater or a girl approaching to sell girl scout cookies.


Similar scenarios have come up in Texas and Pennsylvania. In the Texas case the officers approached a residence with a similar device, they went to the front door of the residence with the device. Unfortunately, they knew from the sidewalk which residence was actively downloading but didn't write that information in the affidavit. All of the evidence was suppressed the court holding the moment they entered the property with the investigatory tool they were in violation of the Fourth Amendment. In Pennsylvania, an officer had an investigatory tool on a common sidewalk in a condominium complex. The court held there that because the officer never left the common area the actions did not violate the Fourth Amendment.

The take away from these cases is that if you want to use an investigative tool it is clear that the moment you step off of a public access point with that tool you violate the Fourth Amendment. The Jardines case had the effect of extending the curtilage of the house to the property line when officers are attempting to obtain evidence using an investigative tool.