Federal Rule of Civil Procedure 33(a) limits parties to 25 interrogatories, “including all discrete subparts.” The recurring—and often disputed—issue is when subparts are treated as part of a single interrogatory and when they must be counted separately. In the Northern District of California the short answer: it depends on whether the subparts are logically and factually related to a single line of inquiry or instead introduce distinct subjects.
The Rule (and Why It Exists)
Rule 33(a)(1) sets the default cap: 25 interrogatories, including all discrete subparts.
That cap was added to curb abuse. The Advisory Committed explains, the purpose of the numerical limit is not to prevent needed discovery, but to ensure judicial scrutiny before parties make potentially excessive use of interrogatories.[1]
The Advisory Committee also cautioned against gamesmanship: “Parties cannot evade this presumptive limitation through the device of joining as ‘subparts’ questions that seek information about discrete separate subjects.” [2] The Committee did provide one bright line, rule, however: “a question asking about communications of a particular type should be treated as a single interrogatory even though it requests that the time, place, persons present, and contents be stated separately for each such communication.”[3]
The Rule 33 Framework in the Northern District
The Northern District’s local rules track the plain language of Rule 33(a)(1) and require a motion showing good cause to exceed the limit.[4] Although Rule 33 does not define “discrete subparts,” courts in this district have developed a pragmatic, case-by-case approach grounded in substance over form.[5]
Northern District courts generally apply the principle that interrogatory subparts are counted as a single interrogatory when they are “logically or factually subsumed within and necessarily related to the primary question.”[6] In contrast, subparts that reach different subjects, theories, or factual areas are treated as separate interrogatories.
In other words:
If answering the primary question necessarily answers the subparts (because the subparts simply ask for details of the same inquiry), courts tend to treat it as one interrogatory. [7]
If the subpart can be answered fully and independently—without answering the primary question (or vice versa)—it is more likely a separate interrogatory. [8]
If the subpart may be admitted and the primary question denied (or vice versa) – it is more likely a separate interrogatory.[9]
Court have recognized that while here is no bright-line test, the “weight of authority” looks to whether the subparts are logically or factually subsumed and bear a direct relationship to the information requested by the primary question.[10]
Substance controls over formatting with courts focusing on whether the subparts create multiple lines of inquiry rather than one coherent inquiry, regardless of whether the subparts are explicitly broken out alphanumerically.[11]
Application in Patent Litigation
Patent cases in the Northern District provide particularly clear guidance. In Synopsys, Inc. v. ATopTech, Inc., the court held that contention interrogatories seeking the facts, documents, and witnesses supporting a single contention or affirmative defense were logically and factually related and therefore counted as one interrogatory.[12] The court explained that where subparts are directed to different types of information—facts, documents, or persons—but all relate to the same contention, they do not multiply the interrogatory count.
This approach reflects the district’s practical understanding of contention discovery, particularly in complex patent cases where identifying supporting evidence is a natural extension of a single substantive inquiry.
The analysis changes when an interrogatory sweeps in multiple distinct products, patents, or subject matters. In Collaboration Props., Inc. v. Polycom, Inc., the court held that interrogatories addressing 26 different accused products contained 26 discrete subparts—each product representing a separate subject of inquiry.[13] The court rejected attempts to evade Rule 33 by packaging unrelated questions as “subparts.”
Courts outside the Northern District—particularly in the Central District of California—have sometimes taken a stricter view, treating requests for facts, documents, and witnesses as separate subparts. Synopsys acknowledged this split but expressly declined to adopt that approach where the requests relate to a single contention or theory.[14] In the Northern District, substance controls: the question is not how many categories of information are requested, but whether the interrogatory pursues one coherent subject.[15]
Takeaways for Litigants
The Northern District’s approach to counting interrogatories under Rule 33 is functional and context-driven. Subparts are counted collectively when they are logically and factually tied to a single primary question. But courts when an interrogatory reaches multiple products, patents, defenses, or otherwise distinct subjects the putative subparts will be regarded as separate interrogatories.
For practitioners, the lesson is straightforward: draft with discipline. Interrogatories that genuinely seek information on one topic are more likely to survive scrutiny as a single interrogatory, while those that combine multiple independent inquiries—no matter how artfully labeled—risk being counted against the Rule 33 limit.
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[1] “The aim is not to prevent needed discovery, but to provide judicial scrutiny before parties make potentially excessive use of this discovery device. In many cases it will be appropriate for the court to permit a larger number of interrogatories in the scheduling order entered under Rule 16(b)”. Amendments to Federal Rules of Civil Procedure, 146 F.R.D. 401, 676 (1993)
[2] Amendments to Federal Rules of Civil Procedure, 146 F.R.D. 401, 675-676 (1993)
[3] Amendments to Federal Rules of Civil Procedure, 146 F.R.D. 401, 675-676 (1993)
[4] N.D. Cal. Civ. L.R. 33-3.
[5] See Trevino v. ACB Am., Inc., 232 F.R.D. 612, 614 (N.D. Cal. 2006).
[6] Trevino, 232 F.R.D. at 614.
[7] See Superior Commc’ns v. Earhugger, Inc., 257 F.R.D. 215, 218 (N.D. Cal. 2009).
[8] Trevino, 232 F.R.D. at 614.
[9] Safeco of Am. v. Rawstron, 181 F.R.D. 441, 446 (1998).
[10] Chapman v. Cal. Dept. of Ed., No. 01-1780, 2002 WL 3285376 at *1 (N.D. Cal. 2002) (See also Collaboration Props., Inc. v. Polycom, Inc., 224 F.R.D. 473, 475 (N.D. Cal. 2004) (interrogatory limit exceeded where “most of the previous interrogatories asked for information about all of the accused Polycom products (totaling 26 different products)” (emphasis in original).)
[11] Seoul Semiconductor Co., Ltd. v. FEIT Elec. Co., Inc., No. 22-cv-05097, 2024 WL 3086641 at *13 (C.D. Cal. May 23, 2024) (interrogatory seeking priority date for each patent asserted claim constituted discrete subparts where the asserted patents were unrelated); Safeco of Am. v. Rawstron, 181 F.R.D. 441, 444 (C.D. Cal. 1998) (“One question that is easily answered is whether subparts must be separately numbered or lettered to count as multiple interrogatories. The better view is that they need not be, or any party could easily circumvent the rule simply by eliminating the separate numbering or lettering of the subparts.”)
[12] 319 F.R.D. 293, 297–98 (N.D. Cal. 2016).
[13] 224 F.R.D. 473, 475 (N.D. Cal. 2004).
[14] 319 F.R.D. at 298.
[15] Trevino, 232 F.R.D. at 614
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For more information regarding Alto Litigation’s litigation practice, please contact one of Alto Litigation’s partners: Bahram Seyedin-Noor, Bryan Ketroser, Joshua Korr, or Kevin O’Brien.
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