For thirty years before December 2015, the operative phrase in Federal Rule of Civil Procedure 26(b)(1) was “reasonably calculated to lead to the discovery of admissible evidence.” That clause was intended as a relevance standard. In practice it became something closer to a license — a phrase that requesting parties used to justify almost any search of an opponent's email, and that courts felt bound to enforce because the rule, as written, did not give them a clear basis to say no. The 2015 amendments deleted that clause from Rule 26(b)(1) entirely. The Advisory Committee notes are explicit about why: the “reasonably calculated” phrase had been “used by some, incorrectly, to define the scope of discovery,” and the deletion was meant to stop that practice.
What replaced it is the language every litigator now needs to know cold. Discovery is permitted of any nonprivileged matter “relevant to any party's claim or defense and proportional to the needs of the case,” weighing six factors: the importance of the issues at stake, the amount in controversy, the parties' relative access to relevant information, the parties' resources, the importance of the discovery in resolving the issues, and whether the burden or expense of the proposed discovery outweighs its likely benefit. The Committee described the change as restoring proportionality “to its original place in defining the scope of discovery,” and as reinforcing the Rule 26(g) obligation that parties already bore when signing discovery responses. The factors themselves were not new — they had lived in Rule 26(b)(2)(C)(iii) for years — but they had been treated as a backstop for objections rather than a primary constraint on the scope of discovery itself.
The substantive consequence is straightforward. Proportionality is no longer something a producing party raises as an affirmative defense to a request that is otherwise within scope. It is built into the definition of scope. A request that is disproportionate is, by the rule's own text, outside the bounds of permissible discovery. That structural shift is what makes the post-2015 case law so different from what came before, and why a 2026 litigator who is still framing proportionality as “burden objection” is using yesterday's vocabulary to argue today's rule.
The six factors of Rule 26(b)(1) are not weighted, and the Advisory Committee deliberately resisted ranking them. In practice, however, the factors do different work in different cases, and a litigator preparing a proportionality argument should understand what each one is actually capable of carrying. The first factor — the importance of the issues at stake — is not a measure of money. The Committee notes give civil rights and constitutional cases as examples of disputes where importance can justify discovery costs that would look disproportionate measured purely against the dollar amount in controversy. It is the factor a plaintiff in a small-damages discrimination case relies on to defeat a defendant's burden objection.
The second factor — the amount in controversy — is the one most often cited in commercial disputes, and it is the easiest factor to quantify. A $300,000 review estimate on a $750,000 contract claim is a different conversation than the same estimate on a $50 million dispute. The third and fourth factors — the parties' relative access to information and the parties' resources — are the asymmetry factors. They are why a sophisticated corporate defendant cannot use cost as a shield against a pro se plaintiff, and conversely why a small-business defendant facing a Fortune 500 plaintiff can credibly argue that a 30-custodian search is beyond its means even if the data technically exists.
The fifth factor — the importance of the discovery in resolving the issues — is the relevance-weighted version of the analysis. It asks not whether the requested material is relevant in the abstract, but whether it is likely to actually move the case forward. This is the factor that courts use to push back on speculative subpoenas, and it is the factor on which Henry v. Morgan's Hotel Group turned. The sixth factor — the burden-vs-benefit test — is the one that does the most work in practice. It is also the factor most directly engaged by modern eDiscovery cost questions, because the “burden” side of the equation is now quantifiable in a way it was not in 1983. A vendor quote with line items priced per gigabyte and per document gives a court something concrete to weigh against the “likely benefit” side of the inquiry.
The first reported decision to apply the amended Rule 26(b)(1) is Henry v. Morgan's Hotel Group, Inc., 2016 WL 303114 (S.D.N.Y. Jan. 25, 2016). The case is procedurally modest — a magistrate judge's order on a motion to quash three third-party subpoenas in an employment-discrimination matter — but the reasoning is exactly what makes the amended rule consequential. The plaintiff had moved to quash subpoenas issued to his former employers. The defendant argued that the records were relevant to the plaintiff's credibility. The court quashed the subpoenas on the ground that the defendant had not “satisfied the Court that [the subpoenas'] production is proportional to the needs of the case.” Henry, 2016 WL 303114, at *2–*3. The relevance was speculative; the burden on the third parties was concrete; the proportionality factors did the rest. That sentence — the requesting party bearing the burden of establishing proportionality — is the post-2015 framework in miniature.
The intellectual companion to Henry is Magistrate Judge Andrew Peck's opinion in Rio Tinto PLC v. Vale S.A., 306 F.R.D. 125 (S.D.N.Y. 2015), decided just weeks before the December 1 effective date of the 2015 amendments and very much written with them in mind. Rio Tinto is best known for the line that “computer-assisted review now can be considered judicially-approved for use in appropriate cases,” Rio Tinto, 306 F.R.D. at 127, but its proportionality reasoning is the part that has aged best. Judge Peck observed that courts “should not impose a heightened standard on TAR compared to keywords or manual review” precisely because doing so would deter the use of efficient technology — which is itself a proportionality concern. The opinion treats methodology choices (TAR versus keywords versus linear review) as proportionality questions, not as standalone evidentiary disputes. That framing is now the dominant approach in federal court.
Outside the proportionality cases proper, the post-2015 framework also draws on enforcement decisions like Carr v. State Farm Mutual Automobile Insurance Co., No. 3:15-cv-01026 (N.D. Tex. Jan. 21, 2016), which makes the necessary corollary point: proportionality is a limit on the scope of discovery, not a license to ignore discovery obligations entirely. The court in Carr granted a motion to compel and was prepared to award fees under Rule 37 against a party that had simply failed to engage. Read together, Henry, Rio Tinto, and Carr describe the post-2015 equilibrium: courts will quash overbroad discovery, courts will approve proportionate methodologies (including TAR), and courts will sanction non-engagement. The proportionality argument only works for parties who actually show up and propose a workable alternative.
The Henry burden-shift, in one sentence: after 2015, the requesting party bears the burden of demonstrating that its request is proportional to the needs of the case — the producing party does not bear the burden of demonstrating disproportion. Henry v. Morgan's Hotel Group, Inc., 2016 WL 303114, at *2–*3 (S.D.N.Y. Jan. 25, 2016).
The UK arrived at the same proportionality destination by a different route. The leading interlocutory decision is Digicel (St Lucia) Ltd & Ors v. Cable & Wireless plc & Ors [2008] EWHC 2522 (Ch), in which Mr Justice Morgan addressed an application for specific disclosure under CPR rule 31.12 regarding restoration of backup tapes, additional keyword searches, and searches of former employees' email accounts. Two passages from the judgment have become canonical. The first is Morgan J's holding that “the task of deciding what is required by a reasonable search is a task given to the court by the wording of the Rules” — meaning the reasonableness of an electronic search is not a matter that can be left to the producing party's solicitor with only narrow review. The second is the proportionality formulation: “the rules do not require that no stone should be left unturned. This may mean that a relevant document, even ‘a smoking gun’ is not found. This attitude is justified by considerations of proportionality.” Digicel, [2008] EWHC 2522 (Ch) at [51]–[53].
That language predates the US 2015 amendments by seven years, and it captures the same intuition: a discovery regime in which every relevant document must be found, regardless of cost, is not a discovery regime any party can actually comply with. Digicel's practical legacy was to push UK litigants toward early cooperation on keyword lists and custodian selection, and to make clear that unilateral search decisions taken without consulting opposing counsel can result in a court-ordered second search at the producing party's expense. The case is regularly cited in UK practitioner literature as the foundational e-disclosure proportionality authority.
The structural successor to Digicel's proportionality framework is the Disclosure Pilot Scheme, originally Practice Direction 51U and now permanent as PD 57AD in the Business and Property Courts since October 2022. The Pilot's central innovation is the menu of Disclosure Models A through E: Model A (no disclosure), Model B (known adverse documents only), Model C (request-led search-based disclosure), Model D (narrow search-based disclosure for specific issues), and Model E (wide search-based disclosure, ordered only in exceptional cases). Parties select among these models on an issue-by-issue basis, with the Disclosure Review Document (DRD) as the procedural vehicle. The Chancellor's clarification in McParland & Partners Ltd v. Whitehead [2020] EWHC 298 (Ch) at [29] that “Issues for Disclosure” are limited to “key issues in dispute, which the parties consider will need to be determined by the court with some reference to contemporaneous documents” further narrows the gravitational pull of disclosure scope.
The single most important practical lesson from the post-2015 case law is this: courts reward proportionality objections that propose a concrete narrower alternative, and disregard objections that simply argue the request is too expensive. The Advisory Committee notes describe proportionality as a “collective responsibility” of the parties and the court. That framing is not just rhetoric. Magistrates and district judges read “collective responsibility” as a directive to favor parties who engage and to penalize parties who obstruct. A motion that says “the request is overbroad and burdensome” without offering a workable substitute reads, to a 2026 court, as exactly the kind of boilerplate objection the 2015 amendments were designed to discourage.
A proportionality objection that wins typically has four components. First, it quantifies the burden in concrete terms — gigabytes, document counts, vendor cost estimates, attorney hours — rather than asserting burden in the abstract. Second, it benchmarks that burden against one or more of the six Rule 26(b)(1) factors, with the amount in controversy being the most defensible numerator and the burden-vs-benefit ratio being the most defensible denominator. Third, it cites Henry v. Morgan's Hotel Group for the proposition that the requesting party bears the burden of establishing proportionality — this is the burden-shift that the 2015 amendments effected, and many requesting parties still do not understand it. Fourth, and most important, it proposes a specific narrower scope: a custodian-limited collection, a date-range narrowing, a TAR workflow with validation metrics, or a staged production keyed to the most likely-dispositive issues.
The “propose a narrower alternative” pattern matters because of how Rio Tinto framed methodology questions. Judge Peck's reasoning was that parties are generally best situated to select methodologies for ESI production and that courts should approve party-negotiated protocols that include reasonable validation. Rio Tinto, 306 F.R.D. at 127. A proportionality objection that arrives with a draft protocol attached — specifying search terms, sampling methodology, and a TAR validation plan — gives the court something to approve. An objection that arrives without one gives the court nothing to do but rule on the original request. The same lesson runs through the UK Disclosure Pilot's DRD requirement: the Disclosure Review Document exists precisely so that parties cannot fight about scope without first having proposed a structure for resolving the fight.
A proportionality argument is only as credible as the cost numbers behind it. The reason traditional eDiscovery vendor pricing is so vulnerable to a Rule 26(b)(1) challenge is that the line items — per-GB hosting, per-document review, per-entry privilege log fees, per-hour project management — are designed to flex upward as the matter progresses, which makes it impossible for either party to put a single defensible burden number in front of the court. DecoverAI replaces that stack with a single pricing primitive: $60 per gigabyte per month, all-in, with unlimited users and no contracts. Ingestion, OCR, AI relevance and privilege classification, Bates numbering, redaction, privilege log generation, and full production delivery are all included. The math you put in your proportionality brief is the math the platform actually charges.
That predictability matters because of what Henry requires. When a court asks the requesting party to demonstrate that production is proportional to the needs of the case, the producing party who can answer with a published, line-item-free cost is in a meaningfully stronger position than one whose vendor estimate carries a $50,000 standard deviation. The same logic runs through the UK Disclosure Pilot's DRD: the document is built around cost and scope estimates, and a producing party that can offer a fixed all-in price for any of Models B through D removes one of the most contested variables in the disclosure conversation. See the pricing page for the full per-GB breakdown, including how the cost calculator runs against specific data volumes.
The practical effect shows up most clearly in matters where the cost-benefit ratio would otherwise have killed the discovery entirely. In the Tax Credit Investigation case study, DecoverAI processed 30,000 documents in three days, including a complete privilege log, with the client achieving a 98% cost reduction relative to the traditional vendor estimate. That is not a marketing claim about efficiency — it is the kind of cost differential that converts a potentially disproportionate review into a clearly proportionate one, and that gives a producing party the room to offer the broader scope a court is more likely to approve. Proportionality is not just a defense to overbroad discovery. It is a framework for getting to a workable scope quickly — and it works best when the platform underneath the argument has already done the cost work.