Japanese Investigators Want to Seize All Our USBs/SD Cards: Is Bulk Seizure of Storage Media Lawful?

In the modern business environment, small, high-capacity portable storage media such as USB flash drives, SD cards, and external hard drives are ubiquitous. They hold vast amounts of company data, from confidential internal documents to intellectual property and routine communications. When Japanese criminal investigators execute a search warrant at a company, they may encounter numerous such devices. This raises a critical question: Can authorities legally seize these storage media in bulk without first individually reviewing their contents to confirm relevance to the investigation? This practice, if overly broad, could lead to the seizure of vast quantities of irrelevant and sensitive company information.

This article examines the legality of bulk seizure of external storage media in Japan, focusing on the key legal precedents and the conditions under which such a measure might be considered lawful.

The Nature of Small Storage Media and Investigative Challenges

The characteristics of devices like USB drives and SD cards present unique challenges for traditional evidence seizure protocols:

1. Invisible Contents (不可視性, fukashisei): Unlike paper documents, the content of a digital storage device is not immediately apparent. Its relevance cannot be determined by mere visual inspection of the exterior.
2. Vast Storage Capacity (膨大な情報量, bōdai na jōhō-ryō): A single small device can store terabytes of data, equivalent to millions of pages of documents.
3. Ease of Data Manipulation and Deletion (加工・消去の容易性, kakō shōkyo no yōisei): Data can be quickly altered, encrypted, or erased, often without leaving obvious traces, especially if the user is alerted to an impending search.

Traditionally, when seizing evidence, investigators would ideally review items on-site to determine relevance before confiscation. For digital media, this might involve viewing files on a screen, printing out specific documents, or copying selected data to another device. This targeted approach minimizes the seizure of irrelevant material and respects the owner's privacy and property rights.

However, on-site review of numerous digital storage devices can be fraught with difficulties:

• Risk of Data Destruction: If a suspect is present and uncooperative, they might attempt to delete or destroy data if investigators begin examining devices individually.
• Lack of Cooperation: Suspects or custodians may refuse to provide passwords or assist in accessing the devices. Under Japanese law (e.g., CCP Art. 111-2 concerning requests for cooperation during warrant execution), there are no direct penalties for such refusal in many circumstances.
• Time Constraints and Impracticality: Reviewing the contents of dozens or hundreds of high-capacity drives on-site can be extraordinarily time-consuming, potentially prolonging the search घंटों or even days, causing significant disruption and burden to the searched party.

These challenges necessitate considering whether a "bulk seizure" – seizing all such devices first and reviewing their contents later at a law enforcement facility – is permissible.

The Seminal Precedent: Supreme Court Decision of May 1, 1998

The leading Japanese judicial pronouncement on the bulk seizure of digital storage media without prior on-site content verification is the Supreme Court Decision of May 1, 1998 (Saikō Saibansho Kettei, Heisei 10.5.1, Keishū Vol. 52, No. 4, p. 275).

The case involved the seizure of 108 floppy disks from a suspect. Investigators had received information that the suspect was developing software designed to instantly and irretrievably erase data. Given this heightened risk of evidence destruction, the floppy disks were seized without their individual contents being confirmed at the scene.

The Supreme Court held that such a bulk seizure of storage media, without prior on-site content confirmation, can be lawful under specific, limited circumstances. The Court identified two key conditions that must be met:

1. Probability of Containing Relevant Information (被疑事実に関する情報が記録されている蓋然性, higi jijitsu ni kansuru jōhō ga kirokuされてiru gaizensei): There must be a recognizable probability that the storage media, as a collection or individually, contain information related to the suspected criminal offense for which the warrant was issued.
2. Risk of Evidence Destruction or Other Hindrances to On-Site Review (記録された情報を損壊される危険があるなどの事情, kiroku sareta jōhō o sonkai sareru kiken ga aru nado no jijō): There must be circumstances, such as a demonstrable risk that the recorded information would be destroyed or damaged if investigators attempted to confirm its presence on-site, or other factors making on-site review exceptionally difficult or impractical.

The Court emphasized that, in principle, the relevance of information on storage media should be ascertained, much like with paper documents. Therefore, bulk seizure without content review is an exception driven by necessity and specific risks, not a general entitlement. It is not a license to indiscriminately seize all digital media found.

Relevance of the 1998 Ruling in Light of Subsequent Legal Reforms

Since this 1998 decision, the Japanese Code of Criminal Procedure has undergone further amendments, particularly in 2011 (effective 2012), which introduced more sophisticated methods for handling digital evidence, such as record-order seizures and refined rules for copying data (CCP Art. 110-2).

However, legal commentators, such as Professor Masahide Maeda (as noted in the source material underlying this topic), suggest that the fundamental principles established by the 1998 Supreme Court ruling concerning bulk seizure remain pertinent. This is because situations persist where obtaining custodian cooperation for selective copying is not feasible, or where the immediate and direct seizure of the physical media is deemed necessary due to risks of tampering or destruction. The newer, more nuanced methods of seizure do not entirely obviate the need for, or the legal questions surrounding, bulk seizures in appropriate circumstances.

Synthesized Requirements for Lawful Bulk Seizure

Based on the 1998 Supreme Court decision and subsequent legal understanding, a bulk seizure of storage media without prior, exhaustive on-site content review may be justified if the following conditions are met:

(A) Probable Cause of Relevance for the Collection:
Investigators must have a reasonable basis to believe that the collection of storage media, even if individual items are unmarked or their specific contents unknown, is likely to contain evidence pertinent to the crime under investigation. This doesn't necessarily mean every single device must be relevant, but that the group of devices, due to their location, ownership, or other contextual factors, has a high probability of yielding evidence. For example, numerous unmarked USB drives found in the primary workspace of a suspect in a digital crime case might meet this threshold more easily than a random collection of old family photo SD cards.

(B) Impracticability or Risk of On-Site Review:
A compelling reason must exist as to why individual, on-site review is not a viable option. This typically falls into two categories:
* Risk of Evidence Destruction/Alteration: There's a credible threat that the suspect or others might destroy, alter, hide, or encrypt the data if investigators attempt to review it device by device at the scene. This was a key factor in the 1998 Supreme Court case.
* Practical Impossibility or Undue Burden: The sheer volume of devices or data, or the technical complexity of accessing them on-site, would make individual review so time-consuming as to be practically impossible within a reasonable period, thereby excessively prolonging the search, unduly burdening the occupants, or creating public order issues.

Even when conducting a bulk seizure, investigators are still expected to consider any readily available external indicators that might help assess relevance, such as labels on devices, the context in which they were found (e.g., a work-related USB found on a work desk in a corporate crime investigation), or statements from occupants regarding their contents. The principle of "without confirming contents" primarily applies to the internal digital data when such internal review is risky or impractical at the scene.

Considering Less Intrusive Alternatives

Before resorting to a bulk seizure, investigators should, where feasible, consider less intrusive means of obtaining the evidence. If the suspect or data custodian is cooperative, requesting voluntary submission of specific relevant files or utilizing the on-site data copying provisions (CCP Art. 110-2) might be more appropriate. Bulk seizure should be a measure of last resort when these alternatives are not viable due to non-cooperation, risk, or impracticality.

Post-Seizure Obligations: The Duty to Review and Return

A crucial aspect that follows a lawful bulk seizure is the obligation of the investigating authorities to promptly and diligently examine the seized media at their facility. This review aims to:

1. Identify and isolate the specific data or devices that are actually relevant to the investigation and fall within the scope of the warrant.
2. Ensure that any devices or data found to be irrelevant are returned to their owner without undue delay.

This post-seizure review and return process is a critical safeguard. It ensures that while the initial bulk seizure might be broad due to necessity, the continued retention of property is strictly limited to what is legitimately required for the investigation. Failure to conduct this subsequent review diligently or to return irrelevant items promptly could itself become a point of legal contention. Businesses whose media have been seized should maintain records and proactively follow up regarding the return of non-essential items.

Illustrative Scenarios

To better understand the application of these principles, consider these scenarios:

• Scenario 1: Potentially Unlawful Bulk Seizure (Defamation Case)
  Imagine investigators are searching an individual's home office based on a defamation complaint. They find a box containing 100 old, unlabeled floppy disks in a desk drawer. There is no specific intelligence linking these particular disks to the alleged defamation, nor any indication of data destruction capabilities. Seizing all 100 disks without any attempt to ascertain their general nature or likely relevance would be highly questionable and likely deemed an overbroad, unlawful seizure. The "probability of relevance" for such a disparate collection in a defamation case would be hard to establish without more specific information.
• Scenario 2: Potentially Unlawful Bulk Seizure (Friend's SD Cards)
  During a search of Person A's home for evidence of a crime, Person B (a friend visiting A) is present. Investigators decide to seize three SD cards from Person B's camera bag, even though Person B states they only contain personal vacation photos, and the bag's location (with a camera) supports this. If the warrant is only for Person A's premises and belongings, and there's no specific probable cause that Person B's SD cards contain evidence of Person A's crime (and B is not a suspect), seizing B's cards, especially without consent or individual review (if safe), would likely be unlawful.
• Scenario 3: Potentially Lawful Bulk Seizure (Corporate Fraud with Risk)
  Investigators search the office of a CFO suspected of large-scale corporate fraud involving digital manipulation of financial records. They find 50 unmarked USB drives in the CFO's locked desk. Intelligence suggests the CFO has sophisticated data wiping software and has previously attempted to obstruct investigations. Here, the probability of relevance (CFO's private storage in a financial fraud case) is high, and the risk of destruction is also significant. Bulk seizure of these 50 drives for later forensic examination would likely be deemed lawful under the 1998 Supreme Court principles.
• Scenario 4: Context-Driven Seizure of Managed Media (Corporate Crime)
  In a case of suspected embezzlement using company systems, investigators search a suspect employee's workstation. They find a rack of 30 SD cards, all labeled with official company asset tags and management numbers, in the employee's locked office cabinet. The employee's supervisor confirms these are company-issued cards for work projects but states only the suspect employee would know the precise current contents of each. Given the strong link to the work-related crime, the official nature of the media, and the potential difficulty of reviewing 30 cards individually and quickly on-site while ensuring no tampering, seizing this collection for later examination would likely be considered lawful. The context strongly suggests relevance, even if the exact content of each specific card isn't immediately verified.

Conclusion

The bulk seizure of digital storage media without prior on-site content review is an exceptional measure in Japanese criminal investigations. It is not a default power. The Supreme Court's 1998 decision permits it only when there is a demonstrable probability that the media contain relevant evidence and specific circumstances (such as a high risk of evidence destruction or practical impossibility of on-site review) make such a broad initial seizure necessary.

For businesses, this means that while investigators might have the authority to seize numerous company-owned USB drives, SD cards, or other portable media in one go, there must be a solid legal justification rooted in these principles. Understanding these parameters, coupled with diligent post-seizure follow-up to ensure the prompt review and return of irrelevant materials, is key to navigating such investigative actions and protecting corporate interests. If faced with such a situation, immediate consultation with legal counsel experienced in Japanese criminal procedure is strongly advised.