Probable Cause for Issuance

Probable Cause for Issuance

Federal Rule of Criminal Procedure 41(d)(1) supplies the standard for issuing a warrant. After receiving an affidavit (a written statement of facts sworn under oath) or other information, a magistrate judge, or a state-court judge of record when Rule 41(b) authorizes it, must issue the warrant if there is probable cause to search for and seize a person or property or to install and use a tracking device.¹ Two features of that sentence organize everything below. The word "must" makes issuance mandatory once the showing is made, so a magistrate who finds probable cause has no room to decline because the search seems unwise or intrusive. The test also operates on what the magistrate has received, an affidavit or other information, so the showing can be no stronger than the facts actually placed before the judge. The previous section asked what a warrant may be issued for. This section asks what the sworn facts must establish before the warrant issues, and the answer must connect the items sought to the place to be searched.

The standard has to do two jobs at once, and that explains why it is a practical, probability-based judgment. It must be strict enough to protect people from intrusions based on a hunch, which is why it demands facts that a neutral judge can evaluate and not the officer's bare suspicion. It must also be workable for the officers who write affidavits under time pressure and for the magistrates who review them, often quickly and on an application the person to be searched never sees. A rigid checklist of required details would fail that second job, because it would reject sound showings that happen to omit a listed detail and would make the drafting and reviewing of affidavits more complicated. A flexible standard keeps the focus on whether the facts, taken together, make it fairly likely that the sought items will be found where the affidavit says.

The discussion proceeds in the order a lawyer would test an affidavit. It begins with the practical totality standard itself, then shows how it handles corroborated tips, and then identifies the floor set by bare-bones affidavits that offer only conclusions. Next it covers the deference reviewing courts give to the magistrate's decision, applies the same standard to a drug-dog alert, and ends with the requirement that probable cause reach each particular item and the relevant time frame, which matters most in document searches. The first question is what the standard itself asks of the magistrate.

The Totality Test

The standard that governs a magistrate's decision comes from Illinois v. Gates, which describes the task as a practical, common-sense decision whether, given all the circumstances set forth in the affidavit, including the veracity and basis of knowledge of persons supplying hearsay information, there is a fair probability that contraband or evidence of a crime will be found in a particular place.³ Hearsay information, in this setting, means facts the officer learned from someone else rather than observed personally, which is why so many affidavits rest on informants. Each phrase in that sentence gives the magistrate a separate instruction. The phrase all the circumstances directs the magistrate to read the affidavit as a whole and weigh every fact together, instead of testing the facts one at a time. The phrase fair probability sets the degree of confidence required. The phrase particular place ties that confidence to location, so the showing must make it probable both that the items sought are evidence or contraband and that they are presently at the place described.⁴

Fair probability is a lower threshold than the ones used at trial, and the reason lies in when the warrant decision occurs. Probable cause requires only the probability of criminal activity, not a prima facie showing of it, and proof beyond a reasonable doubt or by a preponderance of the evidence has no place in the magistrate's decision.⁵ A warrant is sought early in an investigation, on facts gathered by one side, before anyone can cross-examine a source or assemble a full record. A standard that demanded trial-level certainty at that stage would make warrants unobtainable in the very cases where the police have a real but incomplete picture. The people who actually apply the standard point the same way, because affidavits are usually drafted by nonlawyers in the haste of an investigation and warrants have long been issued by laypeople, so demands for elaborate technical specificity cannot be reconciled with how the process works.⁶ A footnote in Terry v. Ohio, drawing on Brinegar v. United States, describes the compromise the standard strikes: requiring more would unduly hamper law enforcement, while allowing less would leave law-abiding citizens at the mercy of an officer's whim.⁷

The totality approach replaced a rigid method under which a tip had to satisfy two separate prongs, veracity and basis of knowledge, before it could count at all. Gates abandoned that two-pronged test and reaffirmed the traditional analysis of all the circumstances.⁸ The reason is structural. When each prong stands as an independent requirement, a gap in either one defeats probable cause no matter how strong the rest of the showing is, and the method had grown into what the Court later called a complex superstructure of evidentiary and analytical rules.⁹ Veracity and basis of knowledge did not disappear. Both remain relevant, but each is now one factor in the overall assessment, and a weakness in one can be offset by a strong showing on the other.¹⁰

Compensation follows from what the two factors are for. Each is a way of estimating whether the tip is probably accurate, so they are two routes to one conclusion, and a strong route in one place can make up for a rough stretch in another. Gates gave the example of an informant known for unusually reliable predictions about certain kinds of criminal activity in a locality, and said that such an informant's failure in a particular case to explain thoroughly how the information was acquired should not by itself bar a finding of probable cause.¹¹ The logic also runs in the opposite direction. When the basis of knowledge is detailed and firsthand and the police confirm parts of the account, the confirmed details are themselves evidence that the source is accurate, even if the source has no history at all.

The fact that moved the answer was whether the affidavit gave the magistrate anything to weigh. In the first version, a strong showing on basis of knowledge and the verified details filled the gap left by the unproven source, which is the compensation Gates permits. In the second, a bare conclusion about reliability stood where facts should have been, and the totality analysis had nothing to add up. Affidavits of that second kind mark the floor beneath the flexible standard, and a later section takes them up directly. The flexibility also leaves the magistrate in control, because the magistrate remains free to draw reasonable inferences from the material supplied or to decline to draw them.¹²

The Court has since confirmed that the totality approach governs probable cause generally and is not confined to human informants. In Florida v. Harris, a unanimous Court reversed a state supreme court that had required prosecutors to satisfy a strict evidentiary checklist, led by comprehensive field records, before a drug-detection dog's alert could support probable cause.¹³ The Court called that checklist the antithesis of a totality analysis and the very thing it had criticized in Gates, because a gap on any single item would defeat the State's case however much other proof of reliability it offered.¹⁴ Dog alerts receive their own section below, and the tip in Gates itself is the subject of the next one. Students lose this issue when they treat veracity and basis of knowledge as separate hurdles, since that structure belongs to the test Gates abandoned.¹⁵

Corroborated Tips

The facts of Illinois v. Gates show the totality test working on a tip about which the magistrate knew almost nothing. The police received an anonymous letter that gave the date of Susan Gates's trip to Florida, said that Lance Gates would fly down to drive the car back, supplied the car's license plate number, and stated that the couple kept drugs in their basement.¹⁷ The letter said nothing about who wrote it or how the writer knew these things, so it was blank on both veracity (whether the source is honest and reliable) and basis of knowledge (how the source came by the information).¹⁸ Neither prong of the old two-part test was satisfied on those facts. Under the totality approach, however, the magistrate was free to look past the letter to what the police did next.

The investigation is what the case teaches. The police confirmed the license plate number, learned that Lance Gates had a reputation for drug trafficking and a past arrest for marijuana possession, and verified that the Gateses had made a trip to Florida around the time the letter specified. They also found that he had given a false address on his driver's license and had stayed in a motel room registered in his wife's maiden name.¹⁹ The Court held that these facts, taken together, gave the magistrate a substantial basis for finding a fair probability that drugs would be found in the home and the car, because the corroboration supplied the indications of reliability that the letter lacked.²⁰ The same opinion states the other side of the comparison just as plainly: the letter, standing alone, would not have been sufficient.²¹

Corroboration can fill the gap because of what it shows about the source. A magistrate cannot cross-examine an anonymous writer and so cannot judge the writer's honesty directly. Verification supplies indirect evidence instead. A letter that predicts a particular trip and names a particular car and plate makes statements the police can check, and when they turn out to be true, the writer has shown access to the family's private affairs. A writer with that access is more likely to be right about what the family keeps in its basement, which is why the police needed to confirm many of the details but not every one. That is the offsetting the totality approach permits: the letter was weak on both veracity and basis of knowledge, and the verified details made up for both.²² The rule also has a practical payoff, because it lets officers act on the common anonymous tip without first identifying the informant. The investigation, rather than the writer's identity, supplies the reliability.

The two situations differ in a single fact. In the first, an anonymous letter of this kind arrives and the police confirm its checkable details, and probable cause exists. In the second, the identical letter arrives and the police do nothing, so the magistrate has only an unsigned assertion whose details no one has tested, and probable cause does not exist.²³ The corroboration is also not a free-standing showing. Without the information from the letter, the facts the police gathered on their own could not satisfy probable cause.²⁴ A drug reputation, an old arrest, and an odd motel registration describe a person who might commit a crime, and they do not point to drugs in a particular basement. The tip supplied the specific claim about the house and the car, and the investigation supplied the reason to believe it, so each half was insufficient alone and the two together were enough.

The kind of fact the police confirm also affects how much it proves.

The fact that moved the answer was whether the verified detail was something only a person with inside knowledge would likely know. Students lose this issue when they treat detail that no one has checked as if it were reliability, since the letter in Gates was full of detail and still fell short on its own.²⁵ The next section turns to how a court reviews the magistrate's decision on facts like these after the warrant has been executed.

Bare-Bones Affidavits

The flexible totality standard has a floor, and Illinois v. Gates marks it in the same passage that retires the rigid two-prong method. Once a court moves beyond what the opinion calls "bare bones" affidavits, probable cause no longer lends itself to a prescribed set of rules, and the flexible, common-sense standard governs instead.²⁷ A bare-bones affidavit reports a conclusion that probable cause exists without reporting the facts that would let anyone else test that conclusion. The totality test is a method for weighing facts, so it presupposes that the affidavit contains some. That presupposition explains how the standard can be generous to officers and still have limits: the weighing can be as forgiving as the Court wishes, but it cannot begin until facts are on the page.

The Court's own examples show what a conclusion looks like. In Nathanson v. United States, an affiant swore only that he "has cause to suspect and does believe" that illegally imported liquor was on certain premises, and that statement would not support a warrant.²⁸ In Aguilar v. Texas, officers swore that they had "received reliable information from a credible person and do believe" that heroin was stored in a home, and the Court called that statement likewise inadequate.²⁹ Both affidavits gave the magistrate virtually no basis for any judgment about probable cause, because each offered the affiant's belief and nothing from which the magistrate could form a belief of the magistrate's own.³⁰ The words "reliable" and "credible" are the officer's grades for the source, and grading the source is the very task the magistrate is supposed to perform.

The totality framework explains why these affidavits fail so completely. Veracity and basis of knowledge are two routes to one conclusion, and a strong showing on one can offset weakness on the other.³¹ Offsetting requires something on each side of the scale. In Aguilar, the label "credible" says nothing about how the informant knew heroin was in the house, and it supplies no checkable detail from which honesty could be inferred, so both factors are empty. A strong showing cannot be borrowed from a factor that has no content, and an empty affidavit leaves the totality analysis with nothing to add up.

The purpose of the warrant requirement supplies the reason behind this floor. Gates describes the essential protection as requiring that the usual inferences from the evidence be drawn by a neutral and detached magistrate, instead of by an officer engaged in the often competitive enterprise of ferreting out crime.³² An officer investigating a case wants the search to go forward and is poorly placed to judge whether the evidence justifies it. When the affidavit passes along only that officer's conclusion, the inference has been drawn by the officer after all, and the magistrate's signature merely ratifies it. Gates therefore insists that the magistrate's action cannot be a mere ratification of the bare conclusions of others, and that courts must continue to review the sufficiency of affidavits conscientiously.³³ The same opinion says the totality approach leaves the magistrate free to draw reasonable inferences or to decline to draw them, but that freedom has no work to do unless the affidavit supplies premises to infer from.³⁴

The contrast with the successful side of the line is the contrast between a conclusion and a set of facts. The affidavit in Gates itself gave the magistrate material to weigh, namely the content of the tip and what the police later verified, so the magistrate could reach a fair probability through inference and did not have to take anyone's word for it.³⁵ A pair of invented affidavits shows how little needs to change to cross the floor.

The fact that moved the answer was whether the affidavit reported what the informant saw and what the police verified, or only a grade for the informant. Students lose this issue when they read the totality test as permission to accept a label such as "reliable" in place of facts, since the label is exactly what Nathanson and Aguilar rejected.³⁶ The same kind of thin affidavit returns in the discussion of good-faith reliance, where the question becomes whether officers may rely on a warrant issued on so little. First, though, the next section takes up how a court reviews a magistrate's decision when the affidavit is not bare.

Deference on Review

A warrant is usually tested after the search has already happened, when the defendant moves to suppress what the officers found and a judge must decide whether the magistrate was right to sign it. The standard for that second look is narrower than the question the magistrate faced. In Illinois v. Gates the Court said that the duty of a reviewing court is simply to ensure that the magistrate had a "substantial basis" for concluding that probable cause existed.³⁸ The magistrate asked whether, on all the circumstances in the affidavit, there was a fair probability that evidence would be found. The reviewing court asks only whether the magistrate had a substantial basis for answering yes. Because the second question is easier to satisfy than the first, a warrant can survive review even when the reviewing judge, starting fresh, would have found the showing closer than the magistrate did.

That is why the Court rejects de novo review, which means a fresh look in which the reviewing court decides the question for itself and substitutes its own judgment for the magistrate's. The Court has repeatedly said that after-the-fact scrutiny of an affidavit should not take that form, and that a magistrate's determination of probable cause deserves "great deference" from reviewing courts.³⁹ A grudging or negative attitude toward warrants is inconsistent with the Fourth Amendment's strong preference for searches made under a warrant, and courts should not invalidate a warrant by reading its affidavit in a hypertechnical rather than a commonsense manner.⁴⁰ Gates itself applied the standard in this way to the anonymous letter and the police corroboration described in the last section, taking the magistrate's finding as the starting point and asking whether the affidavit supplied a basis for it.

The deference rests on two separate reasons, and the first is practical. Affidavits are normally drafted by nonlawyers in the midst and haste of a criminal investigation, so the technical requirements of elaborate specificity once enforced under common-law pleading have no proper place in this area.⁴¹ Warrants have also long been issued by people who are neither lawyers nor judges and who do not keep up with every judicial refinement of probable cause.⁴² A reviewing court that demanded lawyerly precision would hold both the officer who wrote the document and the magistrate who read it to a standard that neither was ever expected to meet. Many warrants are properly issued on the nontechnical, common-sense judgments of laypeople applying a standard less demanding than those of a formal trial, and review has to fit that setting.⁴³

The second reason concerns incentives, and it is the subtler one. If courts subjected affidavits to the closest possible scrutiny, officers might resort to warrantless searches and hope to rely on consent or some other exception to the warrant requirement.⁴⁴ The chain is short. An officer who obtains a warrant risks losing the evidence if a reviewing judge later finds a technical flaw in the affidavit. An officer who searches with no warrant at all may later defend the search under an exception, and so avoids that risk. Strict review would therefore reward bypassing the magistrate, the neutral check that the warrant requirement exists to supply. A warrant in the officer's hand also tells the person whose property is searched that the search is lawful, why it is needed, and how far it may go, which reduces the sense of intrusion.⁴⁵ Gates reaffirmed the substantial-basis standard because it better serves the goal of encouraging officers to use the warrant procedure.⁴⁶

Deference has a floor, and it is the floor identified in the last section. The same passage of Gates that calls for substantial-basis review also instructs courts to keep reviewing the sufficiency of affidavits conscientiously, so that a magistrate does not abdicate the duty to evaluate the facts.⁴⁷ The reason is structural. Deference is owed to a judgment, and an affidavit that states only a conclusion, like the statements rejected in Nathanson and Aguilar, gives the magistrate nothing to judge, so signing it merely ratifies the conclusions of others.⁴⁸ A reviewing court that finds only a bare conclusion on the page has no substantial basis to defer to. Deference attaches to a magistrate's weighing of facts, so an affidavit with no facts leaves nothing for it to attach to.

The fact that moved the answer was the reviewing judge's method, since the affidavit stayed the same in both versions. The first judge asked whether the magistrate had a substantial basis and respected a close call, while the second reread the document for missing formulas. The trap on an exam is treating suppression review as a second probable-cause hearing, because the reviewing court never decides probable cause afresh. The next section moves from informants to a different kind of evidence and shows the same totality standard applied to a trained drug-detection dog's alert.

Drug-Dog Alerts

The totality standard is a general method for deciding probable cause, and an informant's tip is only one of the kinds of evidence it weighs. A narcotics-detection dog's alert tests the method well, because a dog cannot swear an affidavit or explain how it knows what it knows, so the only way to judge the alert is to judge the dog's record. The remaining question is what kind of record the law demands. In Florida v. Harris the Court held that a trained and certified dog's alert can supply probable cause, absent special circumstances that undermine its reliability, and that formal field-performance statistics are not a required ingredient.⁵⁰ The decision carries the flexible, common-sense approach of Illinois v. Gates over to this new kind of evidence.⁵¹

The case came out of a traffic stop. An officer pulled over a driver, noticed nervousness and an open beer can, and asked to search the truck; when consent was refused, the officer walked a trained dog named Aldo around the vehicle, and Aldo alerted at the driver's-side door handle. The search that followed turned up nothing Aldo was trained to detect, but it did reveal pseudoephedrine and other ingredients for making methamphetamine.⁵² Because the search was warrantless, the setting belongs to the study of vehicle searches. What matters here is that the Court was answering the question every probable-cause showing must answer, which is whether there is a fair probability that contraband will be found. A magistrate asks that same question when a warrant affidavit relies on a dog's alert, so the reasoning of the decision applies to affidavits as well.⁵³

The Florida Supreme Court had adopted a checklist. It held that a wide array of evidence was always necessary, including field records showing how often the dog had alerted falsely, and that an officer who kept no such records could never have probable cause to trust the dog.⁵⁴ The Court unanimously reversed, because a mandatory list of documents that decides the outcome no matter how much other proof the State offers is the opposite of weighing the totality of the circumstances.⁵⁵ The checklist also rested on a doubtful premise. Field data looks like the best measure of a dog's accuracy, but it may fail to capture the dog's false negatives and may markedly overstate its false positives, whereas records from standard training and certification settings do not suffer from those distortions.⁵⁶ The reason is easy to see. A field alert that yields no drugs gets logged as a mistake even when the dog was reacting to the lingering odor of drugs that had recently been present, and a dog that fails to alert usually ends the encounter, so its misses seldom enter any record. In a controlled setting the testers know where the drugs were hidden, so every response can be scored accurately.

What does suffice is evidence of satisfactory performance in a certification or training program. If a bona fide organization has certified the dog after testing its reliability in a controlled setting, a court can presume, subject to any conflicting evidence, that the dog's alert provides probable cause. The same is true without formal certification if the dog has recently and successfully completed a training program that evaluated its proficiency in locating drugs.⁵⁷ The presumption is a sensible one because the departments that use dogs have their own strong incentive to keep their programs effective. Only an accurate dog lets officers find contraband without incurring unnecessary risks or wasting limited time and resources, so a department that tolerated sloppy training would be paying for its own errors.⁵⁸ The presumption therefore rests on the department's self-interest, which makes training records a trustworthy stand-in for field statistics.

A presumption is not a conclusion, and the defendant keeps a real opportunity to fight it. The defense may cross-examine the testifying officer or call its own fact and expert witnesses, and it may contest the adequacy of the program by arguing that the standards were too lax or the methods faulty. It may also examine how the dog and handler performed in the assessments, and field history, though prone to misreading, may sometimes be relevant. Even a generally reliable dog's alert can be undercut by the circumstances of the particular search, such as the officer cueing the dog, consciously or not, or the team working under unfamiliar conditions.⁵⁹ The hearing then proceeds like any other. If the State has produced proof from controlled settings that the dog performs reliably and the defendant has not contested it, the court should find probable cause; if the defendant has challenged the dog's reliability overall or the reliability of the particular alert, the court weighs the competing evidence.⁶⁰ In every case the question is whether all the facts surrounding the alert, viewed through the lens of common sense, would make a reasonably prudent person think a search would reveal contraband or evidence of a crime.⁶¹

Aldo's record shows the rule operating in the State's favor. Two years before the search he had finished a 120-hour narcotics-detection program and had separately earned a certification from an independent company. That certification expired after a year, but the sheriff's office required continuing training, and Aldo and his handler completed a 40-hour program a year before the search and then worked together four hours each week on exercises meant to keep their skills sharp. The handler testified, and written records confirmed, that Aldo always performed at the highest level in those settings.⁶² The defense did not contest the quality of that training and concentrated on the certification and on Aldo's field performance, particularly the two stops of this driver's truck.⁶³ Those two alerts had not produced anything Aldo was trained to detect, but the defendant's own regular methamphetamine use could have left residual odor on the door handle, so they did not outweigh the training proof, and the alert supplied probable cause.⁶⁴

The fact that moved the answer was whether anything contested the training proof, since the dog's credentials stayed constant. The same logic governs how an affidavit should be written. An affidavit that reports the dog's certification and recent training gives the magistrate facts to weigh, while one that says only that a reliable dog alerted offers a grade in place of facts, which is the defect the bare-bones cases identify. The trap on an exam is demanding field-performance statistics as a mandatory element, because the absence of such records does not defeat probable cause when the training and certification evidence shows reliability and the defendant has not rebutted it.⁶⁵

Probable Cause by Item and Time

Probable cause is easy to picture as a single finding about a single suspect, but a search warrant needs a finding aimed at each thing the officers will take. The showing for a search has two links, and both must hold for every item the warrant names: there must be a fair probability that the item is evidence of criminal activity, and a fair probability that it is presently located at the place the warrant describes.⁶⁷ Probable cause to arrest asks a different pair of questions, whether a crime occurred and whether this person committed it, so a strong showing that a crime happened leaves the search question open.⁶⁸ That gap is widest when the target is paperwork. In a search for documents, the hard question is whether particular documents are evidence of the crime, because the occurrence of the crime itself is usually the easier showing.⁶⁹ Documents therefore supply the clearest lessons about matching a showing to items and to time.

The reason for tying the showing to each category lies in what a magistrate's approval certifies. A magistrate who finds that a fraud probably occurred has found one fact, and a business under suspicion does not turn every record it keeps into evidence of that fraud merely by being suspected. If a showing about the crime alone could carry any item, the reach of the warrant would be set by what the investigators wished to examine rather than by what the affidavit established, and the neutral check that the warrant clause provides would approve a breadth that no neutral person had looked at. Matching the showing to each type of document keeps the warrant from growing beyond the finding behind it. The Fourth Amendment names both pressure points, since the warrant clause conditions a warrant on probable cause and on a particular description of the things to be seized, and in document cases the first stumbling block is establishing probable cause for each type of document the government hopes to find.⁷⁰

The item limit appears in United States v. Diaz, where the probable cause rested on reports of a series of fraudulent cash transactions.⁷¹ The court found that those dealings in cash gave an obviously insufficient basis for believing that evidence of the crime would be found in the company's checking-account records.⁷² The logic follows from the two links. A scheme conducted in cash gives the magistrate facts about cash, and those facts supply no reason to expect that bank records contain anything about the scheme, so authority over those records would rest on the investigators' hope rather than on a finding. The same affidavit could still support seizure of the cash records themselves, because the facts that establish the scheme also connect those records to it.

The same decision shows the time limit. The warrant in Diaz authorized seizure of documents that predated the start of the fraudulent transactions by several months, and the supporting affidavit alleged no grounds for believing that the scheme reached back to that earlier date, so the warrant was faulted.⁷³ A showing of probable cause carries a limited time frame, and the records a warrant reaches must have been created within it.⁷⁴ The reason is that probable cause describes only what the facts make probable, and facts about activity that began in a certain month say nothing about whether evidence exists from before it. The frame is not rigid, however, and it need not be limited precisely to the period of the suspect activity, because an earlier period may help to compare similar records from innocent transactions or to assess the possibility of advance planning.⁷⁵ What separates a valid earlier period from an invalid one is whether the affidavit gives a reason for including it.

The fact that moved the answer was the fit between each clause and the facts in the affidavit, since the contractor, the scheme, and the magistrate stayed the same. The ledgers and invoices from March onward were tied to the scheme by the informant's account, while the bank statements and the earlier records had nothing in the affidavit behind them. Deference to the magistrate does not fill that gap, because deference attaches to facts the magistrate weighed, and the affidavit offered none for those two clauses.

Time also runs forward from the moment of the application. The place link asks where the evidence is located, and for an ordinary warrant that means when the application is made, so facts that have gone stale weaken the showing. An anticipatory warrant moves the question to a later moment: it rests on probable cause that evidence will be at a specific place in the future, once a specified triggering condition occurs.⁷⁶ In United States v. Grubbs the Court held that such a warrant may issue even though the contraband is not yet at the location, so long as probable cause exists that it will be there when the warrant is executed.⁷⁷ The affidavit must carry two probabilities: that the triggering condition will occur, and that, if it does, there is a fair probability that evidence will be found at the place.⁷⁸ The triggering condition itself need not be written on the warrant.

The item-by-item requirement has a limit that follows from its own logic. Where an organization is permeated by fraud, probable cause may support seizing all of its current records, because when nearly everything a business does belongs to the scheme, nearly every record is evidence and the showing for each category is satisfied at once.⁷⁹ The boundary appears in the Ninth Circuit's decision in In re Grand Jury Investigation Concerning Solid State Devices, which treated that analysis as inapplicable to a business that routinely engaged in fraud but also carried on some legitimate activity, in contrast to a business that is a fraud from top to bottom.⁸⁰ The legitimate side of a mixed business generates records of its own, and nothing in the affidavit makes those records evidence. A caution comes from the Tenth Circuit's decision in Voss v. Bergsgaard, which reasons that even a pervasively criminal enterprise does not permit a warrant that refers simply to all records, because the warrant must still identify the particular types of records relevant to the particular crime, even where that description ends up reaching every record the business holds.⁸¹

Students lose this issue when they treat probable cause that a crime occurred as probable cause for every record, because the showing must reach each item and the period in which it was created. The two-way fit returns in the particular-description requirement, taken up after the mechanics of issuance: probable cause for an item and the warrant's description of that item must line up, so an affidavit that supports cash ledgers cannot be stretched by a description that sweeps in bank statements.