What is the impact of redacted affidavits in the context of a search warrant application?

In reviewing the magistrate's decision that probable cause existed, we are limited to the information contained within the four corners of the affidavits supporting the application for the search warrant. United States v. Stanert, 762 F.2d 775, 778 (9th Cir.), amended, 769 F.2d 1410 (1985). The redacted affidavits in this case contained even less proof than that known to the agents who seized the residence, and thus were deficient for the same reasons as discussed above. ⁴ We therefore find that the magistrate's determination that sufficient probable cause existed to issue the warrant was clearly erroneous.