The way police do their investigative work can have a big impact on criminal prosecution. Police are bound by various rules designed to protect the rights of criminal suspects, and failure to abide by these rules can taint an investigation. An example of this would be when police conduct an illegal search for drugs which yields incriminating evidence. When this happens, one of the protections available to a defendant is to have that evidence excluded from trial. This can obviously weaken the prosecution’s case.
One police investigation tactic used in the state of Florida and elsewhere is the knock-and-talk search. With this approach, police can walk up to suspicious residences, knock on the door and attempt to engage in conversation with the intent to screen for suspicious activity. In the course of this approach, officers often ask for permission to search the home. If the resident gives permission, police do not need a warrant.
Knock-and-talk is legal in the state of Florida and elsewhere, but there are limits on how police can use this approach. For instance, police may approach a home and engage a resident in conversation, but may not amplify their investigation by bringing a drug sniffing dog with them. Neither may police remain at the residence for periods of time and in a manner beyond what an ordinary citizen would legally do. The idea behind this limitation is that knock-and-talk is justified on the basis that it isn’t really a search. Factors like bringing in a drug sniffing canine and guns, or knocking and yelling for long periods of time are tantamount to searches, though, and police need a warrant to conduct a search.
Those accused of criminal activity following an illegal police search really need to work with an experienced criminal defense attorney to ensure they build a strong defense case. Doing so will ensure their interests are represented and that prosecutors are held to their full burden of proof.
Source: Washington Post, “Police can’t knock on your door and wait at front steps forever, court holds,” Orin Kerr, May 1, 2014.