Definition
Working days are days on which ordinary business or labor is conducted, as distinguished from days excluded by law, custom, or contract. In legal contexts, the term typically means all calendar days except Sundays and recognized legal or public holidays. What counts as a "working day" can vary significantly depending on the governing instrument — a statute, contract, or court rule — and the industry or jurisdiction in which the term appears.
The term arises most frequently in three distinct contexts:
1. Maritime and shipping law (lay-days and demurrage). When a charter party or shipping contract specifies a number of "working days" for loading or unloading cargo, Sundays and customs-house holidays are excluded from the count. This is the primary context addressed by the historical dictionaries.
2. Statutory and regulatory deadlines. Many statutes and agency rules specify deadlines in working days rather than calendar days, meaning weekends and official holidays do not count against the running period. The IRS notice-of-deficiency rules and various administrative response deadlines use this framework.
3. Employment and labor law. Statutes governing termination notices, return-to-work requirements, leave entitlements, and wage payment timing often count days in working-day terms, sometimes further refined by the employee's scheduled workweek.
Common Language
Modern common usage (Wiktionary): Plural of working day — a day on which one works; a day that is not a weekend or holiday.
Historical common usage (Webster's 1913): A day on which work is performed, as distinguished from Sunday or a holiday; also, the part of a day during which work is done.
The common and legal meanings are closely aligned, but the legal term carries operational precision the common meaning does not. In a contract or statute, "working days" is a defined count that excludes specific categories of days — and courts have enforced that exclusion strictly. Port customs, local holidays, and industry-specific practices can further narrow or expand which days qualify, making the term more variable in legal application than its plain-English equivalent suggests.
Common Confusion
Working days versus calendar days versus business days: These three terms are not interchangeable and should not be assumed equivalent. Calendar days count every day without exception. Business days typically exclude weekends and federal (or state) holidays but may not account for local or industry-specific customs. Working days may additionally exclude days on which, by established trade custom, work is not performed — such as, in the maritime context, the day of a dockworker's funeral (see Bouvier's, citing 84 Fed. Rep. 688). When interpreting a deadline or computing a demurrage period, the precise term used in the governing document controls, and researchers should not assume any of these three terms means the same as the others.
Why It Matters in Research
The most important research trap with "working days" is treating it as a synonym for "business days" or "calendar days." Courts have rejected that equation in both maritime and administrative contexts. The exclusions that apply depend on the specific contract, statute, or port custom at issue — not on a universal definition.
In maritime research: Historical sources focus almost exclusively on lay-days and demurrage. If you are researching a charter party dispute from the 19th or early 20th century, the relevant question is what customs were recognized at the particular port. Bouvier's citation to 84 Fed. 688 shows that even the death of a fellow dockworker could, by established custom, remove a day from the working-day count. This granularity will not appear in the dictionary definitions; it requires case law specific to the port and trade.
In administrative law research: When statutes or regulations use "working days" to set response deadlines — IRS deficiency notices, NLRB proceedings, and similar contexts — the exclusions are set by the governing statute or agency rule, not by general common law. Researchers should identify the specific regulatory framework and check whether the agency has issued interpretive guidance defining which days are excluded.
In employment law research: Return-to-work deadlines, WARN Act notice periods, and similar employment statutes sometimes specify working days. Here the employee's scheduled workweek may be relevant — a day that is a working day for one employee may not be for another on a different schedule. Modern employment statutes often define the term expressly; check the definitional section of the statute before relying on common law meaning.
Across all contexts: The term's meaning in pre-20th-century sources is almost entirely maritime. Researchers applying historical dictionary definitions to modern statutory or employment contexts should use caution; the corpus of case law applying the term in those contexts developed largely in the 20th century and may depart from the historical baseline.
Historical Dictionary Support
Black's Law Dictionary (both the first and second editions) defines working days exclusively in the maritime context, citing Bell's Commentaries for the proposition that Sundays and custom-house holidays are excluded from the lay-day computation. The two editions are substantively identical on this point, reflecting that the term's legal development was well-settled in the shipping trade by the time both editions were published.
Bouvier's Law Dictionary adds meaningfully to the picture. It incorporates the maritime baseline from Bell but extends it with a federal case (84 Fed. Rep. 688) establishing that port customs — specifically, the practice of stopping work on the day of a dockworker's funeral — can further qualify which days are working days. This is the only historical source among the three that acknowledges industry custom as a modifier, and it is the most useful for researchers working on late 19th-century or early 20th-century maritime disputes.
What all three historical sources miss: They do not address working days in statutory, administrative, or employment contexts — uses that became prominent only in the 20th century. Researchers working in those areas should treat the historical dictionary entries as background only and turn to the relevant statutory text and modern case law.
Jurisdictional Note
In U.S. maritime law, the federal courts apply a national standard, but port-specific customs remain legally cognizable and can affect the working-day count. In administrative and employment law, definitions of working days are frequently set by state statute and vary considerably; some states expressly define the term, while others leave it to common law inference. International shipping contracts may incorporate different conventions depending on the governing law clause.
Encyclopedia Cross-Reference
IRS Notice of Deficiency — 90-Day Letter (The Law Mind Tax Encyclopedia) [tax_133]: Relevant where statutory deadlines are expressed in days and the question arises whether working days or calendar days govern.
Return-to-Work, Light Duty, and Vocational Rehabilitation (The Law Mind Employment & Labor Law Encyclopedia) [employment_112]: Relevant to working-day computations in the employment and workers' compensation context.