The US Supreme Court, in a decision written by Justice Scalia, ruled recently that if police enter a citizen’s curtilage in order to have a dog sniff for potential drugs in the house the police have violated the 4th Amendment because they are outside of the scope of the implied invitation to walk to the door and knock in order to contact the citizen living there.  Florida v. Jardines, the case  a 5-4 decision is a very interesting read if for no other reason than the split among the court. Justice Elena Kagan issued a concurring opinion, in which Justices Ruth Bader Ginsburg and Sonia Sotomayor joined. Justice Samuel A. Alito, Jr. issued a dissenting opinion, in which Chief Justice John G. Roberts, Jr. and Justices Anthony M. Kennedy and Stephen G. Breyer joined. You can access the oral argument via this link.  But the best quote of the case is:

“To find a visitor knocking on the door is routine (even if sometimes unwelcome); to spot that same visitor exploring the front path with a metal detector, or marching his bloodhound into the garden before saying hello and asking permission, would inspire most of us to—well, call the police.”