This is a great case to review the Knock and Talk Exception.
From the case:
This so-called knock-and-talk exception to the warrant requirement is founded on the “implicit license” all of us, including law enforcement officers, enjoy to approach the home by the front path, knock promptly, wait briefly to be received, and then (absent invitation to linger longer) leave. When officers objectively exceed the scope of this license, the knock-and-talk exception cannot justify their warrantless intrusion of the curtilage.
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