To obtain a search warrant, law enforcement officers must submit either a written and sworn affidavit or provide sworn oral testimony. The affidavit or oral testimony must demonstrate probable cause to believe a crime was committed and request authority to search the place and seize the item as evidence or instrumentalities of the crime or as contraband. The warrant itself must specify with particularity the places to be searched and the items to be seized. [U.S. Constitution, Amend. IV.] A warrant will state the times and dates during which it may be executed. A copy and a receipt for the property seized must be left with the person from whom the property was seized.
The good faith exception
The United States Supreme Court has held that evidence seized in good faith reliance on a warrant will not be suppressed. However, the Court noted four situations in which a warrant will not protect a search and suppression of the evidence seized remains an appropriate remedy:  When the magistrate or judge in issuing a warrant was misled by information in an affidavit that the person signing the affidavit knew was false or would have known was false except for his reckless disregard of the truth.  When the magistrate abandons his judicial role by participating in the search and directing officers to seize items not mentioned in the warrant.  When the affidavit shows that probable cause is so lacking as to render official belief in its existence entirely unreasonable.  When the warrant is so facially deficient—i.e., in failing to identify the place to be searched or the things to be seized—that the executing officers cannot reasonably presume it to be valid.
The good faith exception has made attacking searches conducted pursuant to a warrant more difficult. However, courts are willing to find some warrants so deficient that reliance on them is unreasonable, or to rule that the police unreasonably exceeded the scope of a warrant. Additionally, many state courts refuse to follow the good faith exception.
The warrant should specify the crimes to which the evidence relates in order to avoid a general search. The search warrant affidavit may establish probable cause to believe that a particular individual committed the crime under investigation, but if the warrant authorizes a search for items that lack a probable cause connection to the crime under investigation, it is impermissibly overbroad. For example, one court decided that a warrant authorizing the seizure of “all files” in an insurance fraud investigation of a doctor was overbroad and that all evidence seized as a result of the deficient warrant should have been suppressed. It has become common for prosecutors to seek warrants for computers in all investigations, but since defendants rarely plan violent crimes on their computers, the warrant can be challenged as overbroad if it contains no specific allegations connecting the computer to the crime.
Officers’ experience and expectations
Officers sometimes try to supply the missing connection between the crime and the evidence by stating in the affidavit that in their experience as investigators of similar crimes, they often find evidence of the crime in such a place—a home, or on a computer, for instance. Courts have become skeptical of such allegations especially when they are boilerplate with little connection to the facts of the case. A criminal defense attorney should consider consulting an investigator or retired officer to determine whether such a statement has any basis. If not, the warrant can be challenged.
Identification of items to be seized
Warrants must describe the places to be searched and items to be seized with particularity. The warrant must make clear to the executing officer exactly what it is that he or she is authorized to search for and seize. A criminal attorney should compare the list of items for which the warrant authorizes seizure with the supporting affidavit’s assertions about those items to ensure that the warrant was sufficiently particular and not overbroad. If the warrant does not sufficiently describe the place to be searched or the items to be seized, the defect cannot be remedied by the supporting affidavit or the searching officer’s oral description of the items for which he is searching. However, the defect can be remedied by the affidavit if it is attached to or served along with the warrant. Where the items to be seized are books and the basis for their seizure is the ideas they contain, a higher degree of particularity is demanded. This increased particularity applies most often to obscenity investigations. Nevertheless, a criminal attorney should argue for its application when computers are searched as well, because individuals store the most personal and private of writings, photographs, and thoughts on computers.
Unsealing search warrant affidavits
The probable cause affidavit that the magistrate considered in issuing the warrant is a separate document. Often, it is not served with the warrant; rather, the prosecution obtains an order sealing it at least until an indictment issues. The law on the target’s and the public’s right to unseal the affidavit is unsettled:
- Some courts have held that the First and Fourth Amendments erect a presumption in favor of unsealing, and the prosecution has the burden of showing a compelling need to continue the sealing and the absence of any less restrictive means to serve that need.
- Other courts hold that there is no right to access an affidavit, at least pre-indictment.
The affidavit can be of great value. It often contains a comprehensive picture of the evidence against the suspect at the time the warrant was issued. However, in a news-worthy investigation it may not be a good idea for the defense attorney to try to convince the court to unseal the affidavit. Once the affidavit is unsealed, it becomes a public record, and the media can read and report any damning rumors and hearsay it may contain.