## Facts

- Houston police officers sought a state search warrant to search Nick Alford Aguilar’s home for narcotics.
- The warrant application relied solely on a brief affidavit stating the officers had received “reliable information from a credible person” that heroin and other narcotics were being kept at the premises for sale and use.
- No additional facts were presented to the issuing magistrate regarding how the informant obtained the information or why the informant was reliable.
- Officers executed the warrant, announced their presence, heard a commotion, forcibly entered, and seized narcotics as Aguilar attempted to dispose of a packet.
- At trial, Aguilar moved to exclude the seized evidence as the product of an unconstitutional warrant; the trial court overruled the objection, and Aguilar was convicted and sentenced to 20 years.
- The Texas Court of Criminal Appeals affirmed, and the U.S. Supreme Court granted review.

## Issues

1. Whether the Fourth and Fourteenth Amendments require the same probable-cause standard for state search warrants as for federal search warrants.
2. Whether a warrant affidavit based on an undisclosed informant’s tip is sufficient when it provides only conclusory assertions of the informant’s credibility and the information’s reliability, without stating underlying circumstances.

## Decision

- The Supreme Court reversed and remanded.
- The Court held that the Fourth Amendment’s warrant requirements, applied to the states through the Fourteenth Amendment, impose the same standard of reasonableness on state and federal search warrants.
- The Court held the affidavit insufficient because it did not provide the magistrate with underlying facts permitting an independent determination of probable cause.
- Because the warrant was invalid, the evidence seized under it should not have been admitted.

## Legal Principles

- Probable cause determinations must be made by a neutral magistrate based on facts presented, not merely by accepting officers’ conclusions.
- A warrant affidavit may rely on hearsay, including an informant’s tip, but must provide:
  - underlying circumstances showing the basis of the informant’s knowledge; and
  - underlying circumstances supporting the affiant’s conclusion that the informant is credible or the information is reliable.
- Reviewing courts evaluating a warrant’s validity consider only the information that was actually presented to the issuing magistrate.
- A bare statement that officers received “reliable information from a credible person,” without supporting facts, is too conclusory to establish probable cause.

## Conclusion

The Court invalidated a search warrant issued on a conclusory informant-based affidavit, requiring that magistrates be given sufficient underlying facts to independently assess both the informant’s basis of knowledge and the informant’s credibility or the reliability of the information.


Aguilar v. Texas, 378 U.S. 108 (1964)