Please answer a question about the following article about Federal Bureau of Investigation:

The USA PATRIOT Act increased the powers allotted to the FBI, especially in wiretapping and monitoring of Internet activity. One of the most controversial provisions of the act is the so-called sneak and peek provision, granting the FBI powers to search a house while the residents are away, and not requiring them to notify the residents for several weeks afterwards. Under the PATRIOT Act's provisions, the FBI also resumed inquiring into the library records of those who are suspected of terrorism (something it had supposedly not done since the 1970s).

What was one of the most controversial parts of the Patriot Act?
sneak and peek provision