Ad seriatim is a Latin phrase meaning “in a series” or “one after another.” It describes any process in which items are addressed individually and in order rather than lumped together. The term appears across three main settings: judicial opinions, parliamentary procedure, and insurance reporting. In each, the core idea is the same. Take things one at a time so nothing gets buried.
Seriatim Opinions in the Courts
In its best-known legal sense, seriatim refers to the old practice of each judge on a panel writing a separate opinion in the same case. Instead of one ruling for the court, every judge explained his own reasoning, one after another. The practice came out of English common law, where judges hearing a case each delivered an oral opinion, and the early U.S. Supreme Court followed the same tradition.1Ballotpedia. Seriatim
American courts moved away from the practice under Chief Justice John Marshall, who joined the bench in 1801. Marshall believed the Court would carry more authority if it spoke with a single voice, and he introduced the “opinion of the Court” format in his first case. He persuaded the other justices to deliberate privately after oral argument and then unite behind one majority opinion.1Ballotpedia. Seriatim
The practical problem with seriatim opinions was simple. When five judges each wrote their own reasoning, lawyers and lower courts had to piece together which legal principles commanded enough agreement to count as binding precedent. A single majority opinion solved that by producing a clear statement of the law.
The practice survives in international tribunals. Article 57 of the Statute of the International Court of Justice allows any judge to deliver a separate opinion whenever the judgment does not represent the unanimous view of the bench.2United Nations. Statute of the International Court of Justice ICJ judges routinely use that right, appending concurring or dissenting opinions that can run longer than the judgment itself.3International Court of Justice. How the Court Works
Working Through Pleadings and Contracts Seriatim
Seriatim handling shows up in everyday litigation too. Federal Rule of Civil Procedure 8(b) requires a party responding to a complaint to admit or deny each allegation made by the opposing side. A defendant has to work through the complaint paragraph by paragraph, taking a position on every numbered allegation. The stakes are real: under the same rule, any allegation left undenied in a required responsive pleading is treated as admitted.4Office of the Law Revision Counsel. 28 USC App Fed R Civ P Rule 8 – General Rules of Pleading
The same point-by-point approach applies in contract disputes. A judge reviewing a challenged agreement may rule on each disputed clause individually rather than issuing a blanket ruling on the contract as a whole. Isolating each provision keeps parties from burying unfavorable details inside broad arguments about the contract’s overall purpose.
Seriatim Consideration in Parliamentary Procedure
Seriatim is also a standard tool for handling long, multi-part documents in meetings. Under Robert’s Rules of Order, a member may move to “consider by paragraph,” also called “consider seriatim,” which directs the body to work through a document section by section rather than debate it as a single block. The motion needs a second and a majority vote.
The presiding officer reads the first paragraph, opens it for debate and amendment, and then moves to the next paragraph once amendments are finished. No vote is taken on individual paragraphs along the way. Each section is amended tentatively, and only after every paragraph has been considered does the body take a single vote on the entire document as amended. Organizations most often use this method when revising bylaws or adopting lengthy resolutions.
Seriatim consideration is not the same as a “division of the question,” where a motion is split into fully separate parts that each receive their own independent vote. With seriatim consideration, the document stays intact as one question throughout; the section-by-section review is just a more thorough way of reaching that single final vote.
Seriatim Data in Insurance
In the insurance industry, “seriatim” refers to policy-level data in which each individual policy is listed as its own line item rather than grouped into averages or categories. Actuaries use the term to describe a dataset where one cell equals one policy, with no grouping, compression, or remapping. That granular data feeds reserve calculations with precision that aggregate methods cannot match.
Regulatory frameworks reflect the point. The National Association of Insurance Commissioners’ 2026 Valuation Manual references “full seriatim model” calculations in its reserve standards for life insurance, treating the seriatim model as the baseline for accuracy even when companies use compression techniques to simplify modeling.5National Association of Insurance Commissioners. 2026 Edition – Valuation Manual During regulatory examinations, state insurance departments may request seriatim schedules listing every active policy, its premium, and its associated reserve to verify that total reported liabilities actually add up. Seriatim reporting catches problems that summary data hides, such as a handful of mispriced policies or miscalculated reserves tucked inside an otherwise healthy-looking aggregate.