This is the first in a series of blogs describing a two-filter method for the identification and mass culling of irrelevant documents. The method is designed for use before commencing a detailed attorney review. The efficacy of any large-scale document review project can be enhanced by this method. In my experience, it not only helps to reduce costs, it also maximizes recall, allowing an attorney to find all of the documents needed for a case quickly and efficiently. I briefly introduced this method, and the diagram shown right illustrating it, at the conclusion of an article on document review quality control published on my personal law blog: Introducing “ei-Recall” – A New Gold Standard for Recall Calculations in Legal Search – Part Three (e-DiscoveryTeam, 2015).

I use the two-filter method in most large projects as part of my multimodal, bottom line driven, AI-Enhanced (i.w. – predictive coding) method of review. I have described segments of this method, including especially predictive coding, in prior articles. They are listed at the bottom of the Legal Search Science website. I also described this process as part of the Electronic Discovery Best Practices website, found at, which outlines my views on the best practices for lawyers doing e-discovery. (Please note that all views expressed here, and my other online writings, are my own personal opinions, and not necessarily those of my law firm or clients.)

The two-filter culling method includes the well-known technology processes of deduplication and deNisting in the first filter. (Note: I always do full horizontal deduplication across all custodians.) Deduplication and deNisting are, however, just technical filters, not based on legal analysis or judgment. They are well-established industry standards and so will I not discuss them further in this blog series.

Click here to view image

Many e-Discovery beginners think that deNisting and deduplication are the end-all of ESI culling, but that is far from true. They are just the beginning. The other methods described here all require legal judgment, and so you cannot just hire an e-discovery vendor to do it, as you can with deduplication and deNisting. Legal judgment is critical to all effective document review, including culling of irrelevant documents before lawyers spend their valuable time in linear review. In my opinion, all legal review teams should employ some type of two-filter culling component.

My thirty-five plus years of experience as a practicing lawyer have shown me that the most reliable way for the magic of justice to happen is by finding the key documents. You find the truth, the whole truth, and nothing but the truth, when you find the key documents needed to complete the picture of what happened and keep witnesses honest. The two-filter method makes it easier to do that.

Deciding cases on the basis of the facts is the way our system of justice adjudicates disputes on the merits in a fair and impartial manner. In today’s information flooded world, that can only happen if we use technology to find relevant evidence quickly and inexpensively. The days of finding the truth in complicated cases by looking at a few files and witness interviews are long gone.

This lengthy series of blogs on two-filter culling will provide a detailed explanation accessible to beginners and eLeet alike. Please subscribe to this blog to be timely notified of the next of many installments.