Fifth Circuit: Constance Westfall v. Jose Luna, et al

Aggressive nature of the knock-and-talk encounter can taint the subsequent consent to search.  When the person who gave consent to the search indicates that she doesn't want the police officers to go into a certain area, consent for that part of the search is withdrawn.  In these circumstances, the qualified immunity of the police officer presents an issue for trial.

http://www.ca5.uscourts.gov/opinions/pub/16/16-11708-CV0.pdf