Whether a search warrant issued by the State Attorney General directing the investigation and serving as prosecutor satisfied the Fourth Amendment requirement of a neutral and detached magistrate.
Holding
No. The warrant was invalid because the Attorney General was not neutral and detached from his own investigation.
Reasoning
The Fourth Amendment places the probable-cause determination in the hands of a neutral judicial officer rather than the law-enforcement officials engaged in the competitive enterprise of investigating crime. That structural safeguard cannot be satisfied by an official who is actively directing the investigation and later prosecuting the accused.
The Court adopted a per se rule of disqualification in this setting. Even though state law authorized the Attorney General, as a justice of the peace, to issue warrants, a prosecutor and chief investigator cannot be expected to maintain the necessary detachment concerning his own case.
The State's claim that probable cause plainly existed did not cure the defect. The warrant procedure matters independently of whether officers could ultimately have established probable cause before a proper magistrate; otherwise, the warrant requirement would be reduced to a formality.