What is chain of custody and how is handling digital evidence any different?

The chain of custody is a fundamental concept that ensures the integrity and reliability of evidence or data across various fields. By meticulously documenting every step from collection to presentation, organizations and legal entities protect themselves against errors and malpractices, thus safeguarding the interests of the parties involved. This article explores the chain of custody of digital evidence and its unique challenges in comparison to physical evidence.

What is Chain of Custody?

Chain of custody refers to the chronological documentation and record-keeping of the handling, transfer, and storage of evidence. Its primary objective is to establish and maintain the integrity and authenticity of evidence from the moment it is collected until its presentation in court. By providing a detailed account of who had access to the evidence and what they did with it, chain of custody ensures that evidence is reliable, credible, and admissible.

The Legal Perspective

From a legal standpoint, the chain of custody acts as a critical safeguard against tampering, contamination, and unauthorized access to evidence. It establishes the groundwork for the admissibility of evidence under the Federal Rules of Evidence, specifically Rules 901(a) and 902, which require that evidence must be authenticated or identified as a condition precedent to admissibility. This ensures that the evidence presented in court is demonstrably the same as when it was initially collected, maintaining its integrity throughout the legal process.

Moreover, documentation of the chain of custody is crucial not only for the prosecution but also for the defense. The defense can challenge the chain of custody of evidence presented against their clients. According to Rule 104(b), this pertains to the relevance of evidence conditioned on the fulfillment of a fact, such as the unbroken chain of custody. Any gaps or inconsistencies in the chain of custody could potentially lead to the exclusion of crucial evidence under these rules, significantly impacting the outcome of a case. This dual scrutiny by both prosecution and defense ensures that all parties uphold the highest standards of evidence handling and integrity.

Challenges in Digital Evidence Handling

Maintaining a digital chain of custody presents unique challenges that stem from the nature of electronic data and the technology used to manage it. These challenges can complicate the process of ensuring that digital evidence remains tamper-proof and reliable for legal, business, and security purposes. Here are some of the main difficulties involved:

1. Volume and Variety of Data: Digital environments generate vast amounts of data from multiple sources like computers, smartphones, cloud services, and IoT devices. Each type has its storage and transmission methods, making standardization of custody procedures difficult.
2. Complexity of Data Storage and Transfer: Data might be stored across different jurisdictions and on various platforms, including cloud services that operate under different legal frameworks. The transfer of data, whether through physical devices or over networks, can also expose it to risks of interception or corruption.
3. Technical Expertise: Handling digital evidence requires a level of technical knowledge that traditional evidence handling might not demand. Specialists need to be familiar with different operating systems, file formats, and data recovery techniques to properly secure and document digital evidence.
4. Rapid Technological Changes: Technology evolves rapidly, which can outpace the legal and procedural guidelines for handling digital evidence. Keeping up with these changes is necessary to ensure the methods for securing and analyzing digital evidence remain current and effective. A relevant example of technological advancement today is the rise of deepfakes, AI-generated media.
5. Tampering and Alteration Risks: Digital data can be altered, deleted, or fabricated without leaving obvious traces. Establishing that digital evidence has not been tampered with requires robust forensic tools and methodologies.
6. Authentication and Integrity: Ensuring the authenticity and integrity of digital data involves cryptographic techniques like hashing and digital signatures. Implementing these technologies requires careful planning and execution to maintain a solid chain of custody.
7. Privacy and Compliance Issues: Digital data often contains sensitive personal information. Maintaining chain of custody must therefore be balanced with compliance with data protection laws and regulations, such as GDPR or HIPAA, which can limit how data is stored, transferred, and accessed.
8. Lack of Standardized Protocols: While there are best practices for handling digital evidence, there is often a lack of standard collection protocols within firms. This leads to a variety of different collection methods across individuals within a firm, opening the door for greater chain of custody scrutiny.

The Impact of Chain of Custody on Court Proceedings

Chain of custody plays a pivotal role in court proceedings, as it directly influences the admissibility and weight of evidence presented. Failure to establish a proper chain of custody may result in evidence being dismissed or contested, potentially undermining the entire case. Several high-profile legal cases illustrate the consequences of failing to maintain a robust digital chain of custody:

1. State v. Casey Anthony (2011): In this notorious case, the prosecution failed to establish a clear chain of custody for some digital evidence, including internet search histories, which weakened the evidence's credibility and played a part in the outcome of the case.
2. Apple Inc. v. Samsung Electronics Co. (Various Dates): In the high-profile patent infringement cases between Apple and Samsung, the digital chain of custody for software code and design documents was crucial. Both parties scrutinized how the opposing side handled and protected confidential digital documents that were submitted as evidence of patent infringement or defense.
3. Lorraine v. Markel American Insurance Company (2007): This case is often cited specifically for its focus on the admissibility of electronic evidence in civil litigation. The court discussed the requirements for establishing a reliable chain of custody along with other factors necessary to admit various types of electronic evidence. This case has become a reference point for understanding how electronic records should be managed and presented in court to meet legal standards.

The Role of Expert Witnesses

Expert witnesses often play a crucial role in explaining the significance of the chain of custody to the court. Their expertise and testimony help educate judges, attorneys, and juries on the importance of maintaining the integrity and admissibility of evidence. By providing insights into the chain of custody process, expert witnesses contribute to a fair and just trial.

Expert witnesses may also be called upon to testify about the handling of evidence, the procedures followed to maintain the chain of custody, and any potential vulnerabilities in the process. Their testimony can shed light on complex technical aspects of evidence handling, helping the court understand the challenges and best practices involved in preserving the chain of custody. This additional layer of expertise further reinforces the credibility of the evidence presented, ensuring that justice is served effectively.

Screenshots, Print to PDF, SnagIt, and Other Basic Capture Methods Compromise Chain of Custody

Screenshots, while convenient, often fall short of the requirements for digital evidence due to several limitations. Unlike specialized digital capture tools, screenshots typically lack crucial metadata such as the time, date, URL, and IP address, which are essential for authenticating the source and context of the evidence and for establishing a precise timeline. 

Furthermore, screenshots are susceptible to manipulation using simple image editing software, making it difficult to prove their authenticity after capture. They also may not capture all necessary details of a digital interaction, such as hidden text or off-screen content, potentially misrepresenting the evidence. Additionally, screenshots taken manually usually lack independent third-party verification, are saved to local devices opening the door for tampering (or accusations of tampering by the opposing side), and are missing detailed documentation required to establish a reliable chain of custody.

For these reasons, legal professionals and experts often try to avoid being in the digital chain of custody altogether and relying on tools like Page Vault to do so. Staying out of the digital chain of custody when possible reduces the risk of accidental alterations to the evidence, and minimizes the legal liabilities and administrative burdens associated with the protocols required for handling and documenting digital evidence.