Under what conditions can a search warrant be considered invalid?

A search warrant can be considered invalid if it is based on false statements included by the affiant. This principle is rooted in the Fourth Amendment's protection against unreasonable searches and seizures. The affiant, who provides information to support the issuance of the warrant, must do so in a truthful manner. If it is later shown that the affidavit contains false statements that were material to the issuance of the warrant, the warrant can be invalidated. This is crucial because the integrity of the information presented to a magistrate or judge is what establishes probable cause for the warrant.

While the other options may present issues related to the warrant, they do not necessarily invalidate it. For example, a lack of signature might render the warrant ineffective, but does not automatically negate the probable cause that might have justified the warrant's original issuance. Similarly, typographical errors might not affect the accuracy of the warrant's content, and a delay in issuance doesn't inherently invalidate the reasons for which it was sought. False statements, particularly those made knowingly or with reckless disregard for the truth, undermine the foundational legitimacy of the warrant itself, making this condition the most critical for determining its validity.