In the world of eDiscovery, legal teams are often required to process and review massive volumes of electronically stored information (ESI). Within this data, a significant percentage is often duplicate content—emails forwarded multiple times, files stored in several locations, or documents sent to multiple custodians.
This is where deduplication becomes essential.
What ?
Deduplication is the process of identifying and removing identical files across a dataset so that only one unique instance of each file is preserved for review.
In eDiscovery platforms, deduplication helps reduce:
The goal is simple:
Process less, review less, and pay less — without losing evidence.
Why ?
With organizations generating terabytes of digital communication and documents, duplicate content becomes inevitable. Deduplication provides several key benefits:
1. Reduces Review Volume
Document review is the most expensive part of eDiscovery. Eliminating duplicates means legal teams review fewer documents while still maintaining the integrity of evidence.
2. Cuts Storage and Processing Costs
By retaining only unique items, processing engines spend less time analyzing and indexing content. Storage footprints shrink, lowering infrastructure or vendor costs.
3. Improves Review Efficiency
Reviewers don’t repeatedly analyze the same email sent to multiple custodians. This prevents reviewer fatigue and improves accuracy.
4. Ensures Consistency
Having only one copy of each document ensures that coding decisions (responsive, privileged, etc.) remain consistent across the case.
Types of Deduplication in eDiscovery
Deduplication can be applied at different levels, depending on the legal strategy and workflow. The two most common methods are:
1. Global Deduplication
Global deduplication means deduplication across the entire dataset, regardless of the custodian.
Example:
If John, Sarah, and David all have the same email, only one copy is retained for the entire review set.
Pros
- Maximum reduction in volume
- Lowest review cost
- Ideal for large datasets or tight budgets
Cons
- Custodian information becomes important—platforms must track “all custodians” associated with the document
- Some legal teams prefer to see duplicates per custodian for review strategy
2. Custodian-Level Deduplication (Per-Custodian)
Here, duplicates are removed only within each custodian’s data.
Example:
If John has 3 copies of the same file, it becomes 1.
But if Sarah also has the same file, her copy is kept separately.
Pros
- Maintains visibility of the document per custodian
- Preferred in situations where who-had-what matters for legal strategy
- Helps preserve context during testimony
Cons
- Higher document review volume compared to global deduplication
- More storage and processing
Conclusion
Deduplication is a foundational part of modern eDiscovery workflows. It ensures that legal teams focus on what truly matters by reducing redundant data, saving substantial cost and time, and improving review quality.
Whether you choose global or custodian-level deduplication depends on your case strategy, budget, and review requirements
Comment or Reach Out to us if you require more details.