Definition
SUBSTITUTES has two principal legal meanings, drawn from distinct areas of law:
1. Scottish Succession Law. In a tailzie (an entailed estate settled upon a series of heirs in succession), the persons designated to inherit after the first-named heir are called "substitutes" or "heirs of tailzie." The first-named heir is the "institute" or "heir-institute"; all subsequent heirs nominated in the series are substitutes. Each substitute takes only if the prior heir fails to take or dies without issue, according to the conditions of the entail.
2. Roman Law (Substitutio Hæredis). In Roman testamentary practice, a testator could name a substitute heir (hæres substitutus) to take in place of the originally instituted heir (hæres institutus) if the instituted heir predeceased the testator, refused the inheritance, or was otherwise unable to take. Multiple grades of substitution were recognized in Roman law, including vulgar substitution, pupillary substitution, and quasi-pupillary substitution — each addressing different contingencies.
3. General Legal Usage. More broadly, across contracts, procedure, and equity, "substitute" or "substitutes" denotes persons or instruments that stand in place of another — a substituted party in litigation, a substituted agreement replacing a prior contract, or a will substitute (such as a revocable trust) that accomplishes testamentary transfer outside the formal will.
Common Language
Modern common usage (Wiktionary): Third-person singular simple present indicative of "substitute" — meaning one thing takes the place of another.
Historical common usage (Webster's 1913): A person or thing put in place of another; one who acts for another.
The common meaning is accurate as far as it goes, but in legal contexts "substitutes" carries a technical term-of-art meaning in Scottish succession law that is not obvious from ordinary usage. A researcher encountering "substitutes" in a Scottish or entail-related source is not simply reading a general reference to replacement — they are encountering a precisely defined class of heirs with specific rights and limitations under the tailzie. The Roman law dimension adds further technical depth that the ordinary word entirely conceals.
Recognized Forms
/SUBTYPES
In Roman law, recognized forms of substitutio hæredis include:
- Vulgar substitution (substitutio vulgaris): The most common form; a fallback heir named in case the institute fails to take.
- Pupillary substitution (substitutio pupillaris): A parent's appointment of a substitute to take on behalf of an impubescent child heir who died before reaching puberty.
- Quasi-pupillary (or exemplary) substitution: Extended the pupillary concept to substitute for an insane or mentally incapacitated descendant.
In Scottish succession law:
- Institute: The first-named heir in the tailzie.
- Substitutes (heirs of tailzie): All subsequently named heirs, taking in the order prescribed by the tailzie.
Why It Matters in Research
The primary research trap with "substitutes" is that the word appears across radically different doctrinal contexts — Scottish entail law, Roman inheritance, contract law (novation and substituted agreements), and estate planning (will substitutes) — without always signaling which context governs. A researcher working in historical sources must identify the jurisdiction and subject matter before assuming any particular meaning applies.
In Scottish legal sources specifically, "substitutes" and "heirs of tailzie" are near-synonymous but not always used interchangeably; Erskine's Institutes is the foundational reference. Researchers using historical Scottish materials should cross-reference the tailzie entry and related entail doctrine to understand the succession mechanics fully.
In contracts research, "substituted agreement" and "novation" are closely related but not identical — a substituted agreement discharges the old contract by replacing it, while novation typically also substitutes a new party. The distinction matters for research into discharge doctrine.
In modern estate planning, "will substitutes" — revocable inter vivos trusts, joint tenancy, beneficiary designations, payable-on-death accounts — represent a major area of doctrinal development in the twentieth century and command their own substantial literature entirely separate from the Scottish or Roman meanings. Researchers encountering "will substitutes" in modern sources should not conflate this usage with the historical heir-substitute concept.
The Roman law entries (substitutio hæredis) appear in historical dictionaries primarily as cross-references and definitions in Latin, and modern readers should be aware that these entries often assume familiarity with Roman succession concepts that are not separately explained.
Historical Dictionary Support
Black's Law Dictionary (both the first and second editions) addresses "substitutes" exclusively in the Scottish law sense, defining the term consistently across editions in the context of tailzie and the institute/substitute distinction. Neither edition addresses the Roman law forms directly under this headword, deferring instead to the separate Latin entry substitutio hæredis.
Bouvier's Law Dictionary aligns with Black's on the Scottish definition and similarly cross-references the tailzie. Bouvier adds a citation to Erskine's Institutes (3.8.8), which is the appropriate primary source for Scottish entail doctrine and worth noting for researchers who need to go beyond the dictionary synthesis. Bouvier also explicitly cross-references hæres for the Roman law dimension rather than elaborating it under this headword.
All three historical dictionaries are notably narrow: they treat "substitutes" as essentially a Scottish succession term and do not address the broader contractual or equitable uses that modern legal research must also navigate. This gap is significant — researchers relying solely on historical dictionary coverage would miss the contracts and estate planning dimensions entirely.
Jurisdictional Note
The Scottish law meaning is specific to Scots law and the entail system, which was substantially reformed and eventually abolished in Scotland by legislation in the nineteenth and twentieth centuries. The Roman law meanings are primarily of historical and comparative interest. The modern American usage — will substitutes, substituted agreements, substituted parties — is the dominant context for U.S. legal research and should not be assumed to align with the historical dictionary definitions.
Encyclopedia Cross-Reference
Novation — Substitution of Parties (The Law Mind Contracts & Commercial Law Encyclopedia)
Discharge — Novation and Substituted Agreement (The Law Mind Contracts & Commercial Law Encyclopedia)
Revocable Inter Vivos Trusts as Will Substitutes (The Law Mind Trusts, Estates & Probate Encyclopedia)