Definition
"As long as" is a conditional or durational phrase used in legal instruments — including statutes, contracts, deeds, wills, and trust documents — to qualify the operation of a grant, obligation, or right. It carries two distinct legal functions depending on context:
1. Durational: Describing the period during which a legal interest, obligation, or right remains in effect. In this sense, "as long as" marks the outer boundary of a grant or duty — it continues for the duration of some condition or status and terminates automatically when that condition ends.
2. Conditional/Prerequisite: Used synonymously with "provided that" or "on condition that," signaling that a legal consequence follows only while a specified condition remains satisfied.
The distinction between these two functions matters enormously in property law. In a conveyance granting land "to A as long as the premises are used for residential purposes," the phrase creates a fee simple determinable — an estate that terminates automatically upon breach of the stated condition, with title reverting to the grantor by operation of law, without any re-entry requirement. This is one of the most consequential uses of the phrase in Anglo-American law and the primary reason it attracts close interpretive attention.
Common Language
Modern common usage (Wiktionary): "As long as" carries two ordinary meanings: (1) for the entire duration that; while; and (2) provided that; assuming some condition is met.
Historical common usage (Webster's 1913): Webster's treats "as long as" as a simple durational or conditional conjunction, equivalent to "while" or "provided."
The gap between common and legal meaning is not in the words themselves but in their legal consequences. In ordinary speech, saying "you can use my car as long as you want" creates no enforceable interest. In a deed or will, the identical phrase can create a determinable estate — a recognized property interest with automatic defeasance and potential future interests. Researchers must resist reading the phrase as merely descriptive when it appears in a conveyancing instrument; courts have held it operative to define the estate granted.
Common Confusion
"As long as" is frequently confused with "on condition that," "provided that," and "but if." These phrases are not interchangeable in property law. "As long as" (and its variants "while," "during," and "until") typically creates a fee simple determinable with a possibility of reverter. "On condition that," "provided that," and "but if" typically create a fee simple subject to condition subsequent, which requires affirmative re-entry by the grantor to terminate the grantee's interest. The practical difference is significant: a determinable estate ends automatically; a conditional estate continues until the grantor acts. Some jurisdictions have partially collapsed this distinction by statute, but the interpretive trap remains live in older deeds and will drafting.
Why It Matters in Research
This phrase is a pivotal interpretive marker in property law research. When searching historical deeds, trust instruments, and older conveyancing forms, the presence of "as long as" signals a potential fee simple determinable — a classification with consequences for future interests (possibility of reverter vs. right of entry), alienability, and merger doctrine.
Trap for historical sources: Older deeds and instruments often use "as long as," "while," and "during" interchangeably without the drafter understanding the doctrinal distinction. Courts in the nineteenth and early twentieth centuries were themselves inconsistent. Researchers using historical case reporters should note that the fee simple determinable / condition subsequent distinction was contested well into the twentieth century, and some older courts treated these phrases as equivalent.
Durational clauses in contracts: Outside property law, "as long as" in commercial contracts governs the duration of license grants, non-compete obligations, and ongoing duties. Ambiguity between durational and conditional readings has generated substantial contract interpretation litigation. When a contract says a royalty is payable "as long as the patent is in force," courts must decide whether expiration of the patent automatically ends the obligation or whether a further act is required.
Trust and estate instruments: In trust documents and wills, "as long as" may govern the duration of income interests, support trusts, and spendthrift protections. These durational phrases interact with rule against perpetuities analysis and termination clauses.
Historical Dictionary Support
Rapalje & Lawrence do not provide a substantive entry for "as long as" as a standalone legal term. The source material retrieved under this entry references the Articles of Union between England and Scotland — an apparently misfiled or misindexed citation unrelated to the phrase itself. Researchers should not rely on Rapalje & Lawrence for guidance on this term.
The absence of a dedicated historical dictionary entry is itself instructive: "as long as" was treated as a phrase whose legal force derived from judicial construction and conveyancing practice rather than from formal doctrinal definition. Its operative significance was worked out through equity and common law courts interpreting grants, not through lexicographers.
Jurisdictional Note
Most American jurisdictions follow the traditional distinction between fee simple determinable ("as long as") and fee simple subject to condition subsequent ("provided that"), but a minority of states have modified or abolished the automatic forfeiture effect of determinable language by statute. Researchers examining instruments in any specific jurisdiction should verify whether the state has enacted legislation affecting defeasible estates before relying on the common law default.