A drug-sniffing dog at your doorstep constitutes a search under the Fourth Amendment of the U.S. Constitution, the Supreme Court has decided.

The high court ruled last month that a Florida police officer’s use of a drug-sniffing dog to search a truck during a routine traffic stop was acceptable, the justices drew the line at the entrance to a private home, USA Today reports.

Writing for a 5-4 majority, Justice Antonin Scalia says that a dog sniffing at a house where police suspect drugs are being grown does not justify the officers’ entry into the home:

“At the Fourth Amendment’s ‘very core’ stands ‘the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion,’” wrote Scalia. The majority opinion also added that the area immediately surrounding and associated with the home is part of the home itself for Fourth Amendment purposes.

Writing in dissent, Justice Samuel Alito wrote that dogs have long been used for law enforcement, and that the homeowner in this case did not have a reasonable expectation of total privacy:

“A reasonable person understands that odors emanating from a house may be detected from locations that are open to the public, and a reasonable person will not count of the strength of those odors remaining within the rage that, while detectable by a dog, cannot be smelled by a human,” Alito wrote.