In the case of Florida v. Jardines the US Supreme Court upheld the Florida Supreme Court’s suppression of drug evidence found after police brought a drug dog to a home to search without consent.  Previous law had held that a drug dog sniff was not a search for 4th Amendment purposes, but the Court found that the privacy of the home was violated by such a search and upheld the Florida Supreme Court’s decision.  Police can no longer just bring a drug dog to the front door to see if it alerts and then search a home.

Follow the below link for detailed information about the case.

http://www.scotusblog.com/case-files/cases/florida-v-jardines/