An anticipatory warrant is “a warrant based upon an affidavit showing probable cause that at some future time (but not presently) certain evidence of crime will be located at a specified place.” 2 W. LaFave, Search and Seizure §3.7(c), p. 398 (4th ed. 2004). Most anticipatory warrants subject their execution to some condition precedent other than the mere passage of time - a so-called “triggering condition.” If the government were to execute an anticipatory warrant before the triggering condition occurred, there would be no reason to believe the item described in the warrant could be found at the searched location; by definition, the triggering condition which establishes probable cause has not yet been satisfied when the warrant is issued. Anticipatory warrants do not contravene the Fourth Amendment’s provision that “no Warrants shall issue, but upon probable cause.”
The Supreme Court and every Court of Appeals to confront the issue, see, e.g., United States v. Loy, 191 F. 3d 360, 364 (CA3 1999) (collecting cases) has held that they do not violate Fourth Amendment mandates. Probable cause exists when “there is a fair probability that contraband or evidence of a crime will be found in a particular place.” ...