The Supreme Court has given some guidance as to how long officers must wait after knocking and announcing their presence before entry may be made. In "U.S. v. Banks", the Supreme Court found 15 to 20 seconds to be a reasonable time where officers received no response after knocking and where officers feared the home occupant may be destroying the drug evidence targeted by the search warrant. As with most other things in the Fourth Amendment arena, the Court left reasonableness of the time period to be determined based on the totality of the circumstances; and thus inferior Federal courts have found even shorter time periods to be reasonable. Some different factors have been propounded by lower courts to guide the analysis of a reasonable wait period. A few examples are: