PS Exam Preparation

Comprehensive preparation for the NCEES Principles and Practice of Surveying (PS) exam. 5 modules covering all 5 exam domains with 50 in-depth topics.

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Lesson 4

Acquiescence & Boundary by Agreement

Learning Objectives

After completing this topic, you should be able to:

Define acquiescence and distinguish it from adverse possession
Explain the doctrine of practical location and its requirements
Identify the elements of a valid boundary by agreement
Describe how estoppel operates in boundary disputes
Distinguish between mutual acquiescence and unilateral encroachment
Recognize evidence of acquiescence in field conditions
Apply these doctrines to determine whether an unwritten boundary has been established

Overview

Acquiescence, practical location, and boundary by agreement are related but distinct doctrines through which property owners can establish boundary lines that differ from the written deed description. Unlike adverse possession, these doctrines typically do not require hostility. Instead, they are grounded in the behavior of adjoining landowners who -- through their actions, silence, or mutual agreement -- establish a boundary line on the ground that becomes legally binding.

As Brown notes in Boundary Control and Legal Principles: unwritten title lines established by estoppel, agreement, or prescription are local in character and cannot be used to establish the lines of a written deed. They create a boundary between specific parcels, but they do not change the deed description itself.

Key Concepts

Acquiescence

Figure PS.1.33 — Three acquiescence requirements

Acquiescence occurs when adjoining landowners treat a particular line as the boundary between their properties for a long period of time, typically at least as long as the statute of limitations for adverse possession. The line becomes the legal boundary regardless of where the "true" line (as described in the deeds) actually lies.

Key characteristics of acquiescence:

Mutual mistake or uncertainty about the true boundary location
Both parties treat the line as the boundary (not unilateral encroachment)
The line is typically marked by a fence, hedge, wall, or other visible feature
The recognition continues for a long period (often the statutory period)
Hostility is NOT required -- this is the critical distinction from adverse possession
Neither party needs to know the line is incorrect

Elements of acquiescence:

Element	Description
Uncertainty or dispute	The true location of the boundary is uncertain or disputed
Recognizable line	A visible line exists on the ground (fence, hedge, etc.)
Mutual recognition	Both adjoining owners treat the line as the boundary
Duration	The recognition continues for the statutory period
Good faith	The parties act in good faith (no fraud or deception)

Example: Two neighbors share a fence that was built 40 years ago. Both families have maintained their respective sides, mowed to the fence line, and treated the fence as the boundary. A modern survey reveals the fence is 3 feet onto one neighbor's property. Despite the survey showing the "true" line, the fence line may be the legal boundary by acquiescence because both parties treated it as such for decades.

Practical Location

Practical location (also called "location by practical construction") occurs when the parties to a deed, or their successors, locate the boundary on the ground and then act upon that location. Once practically located and acted upon, the boundary is fixed even if a more precise survey later shows it was incorrectly placed.

Requirements for practical location:

Uncertainty about the boundary location
An agreement (express or implied) on where the boundary is
Acquiescence to the agreed-upon location for a significant period
The parties or their successors act upon the location (build fences, improvements, etc.)

Practical location is particularly important in the context of original surveys. When an original surveyor placed a monument to mark a corner, and the adjoining owners accepted that monument and built their improvements accordingly, the monument's location becomes the boundary even if it was incorrectly placed relative to the theoretical position.

Boundary by Agreement

Boundary by agreement occurs when adjoining landowners, faced with uncertainty about the true boundary, expressly agree on a boundary line. This is the most straightforward of the unwritten boundary doctrines.

Requirements:

Genuine uncertainty or dispute about the boundary location -- this is essential. If the boundary is clear, the parties cannot simply agree to move it (that would require a deed)
Express or implied agreement to treat a specific line as the boundary
The agreement must be acted upon -- the parties must conduct themselves in accordance with the agreed boundary
The agreement must be fair and reasonable under the circumstances

Important limitation: A boundary by agreement cannot be used to convey land. If two owners simply agree to shift a boundary for convenience (with no genuine uncertainty), that agreement is really an attempted conveyance and must comply with the Statute of Frauds (written instrument, signed, etc.). The doctrine only applies when there is a bona fide uncertainty about where the true boundary lies.

Estoppel

Figure PS.1.34 — Estoppel four-step waterfall

Estoppel prevents a party from asserting a right when their prior conduct would make it unjust to do so. In boundary contexts, estoppel operates when:

One party makes a representation (by words or conduct) about the boundary location
The other party relies on that representation
The relying party changes position to their detriment (builds improvements, etc.)
It would be unjust to allow the first party to now assert a different boundary

Example: Owner A tells Owner B that the boundary is at the fence line. Relying on this statement, Owner B builds a garage that extends to the fence. Owner A cannot later claim the boundary is actually 5 feet on the other side of the fence, because B relied on A's representation and built accordingly.

Types of estoppel relevant to boundary surveying:

Type	Description
Equitable estoppel	Based on representations and detrimental reliance
Estoppel by deed	A grantor who conveys property is estopped from later denying the conveyance
Estoppel by silence	Failure to object when one has a duty to speak
Estoppel by conduct	Actions that induce reasonable reliance by another

Distinguishing the Doctrines

Figure PS.1.32 — Four unwritten boundary doctrines

These related doctrines overlap but have important differences:

Feature	Acquiescence	Practical Location	Agreement	Adverse Possession
Hostility required	No	No	No	Yes
Mutual conduct	Yes	Yes	Yes	No (unilateral)
Express agreement	Not required	Not required	Required	Not applicable
Uncertainty required	Yes	Yes	Yes	Not required
Statutory period	Usually required	Varies	Generally shorter	Required
Tax payment	No	No	No	Often required
Result	Fixed boundary	Fixed boundary	Fixed boundary	Transfer of title

The Role of Fences

Figure PS.1.35 — Fence as evidence: what it proves vs what it doesn't

Fences play a central role in all of these doctrines. However, the surveyor must be careful not to assume that every old fence represents a legal boundary:

A fence may establish a legal boundary when:

Both owners have treated it as the boundary for the statutory period
Improvements were built in reliance on the fence location
The parties expressly agreed the fence was the boundary
The fence was placed by an original surveyor as a boundary marker

A fence does NOT establish a legal boundary when:

It was built for convenience (livestock containment, privacy) with no intent to mark the boundary
One party placed it knowing it was not on the line, and the other party was unaware
It was placed with the permission of the adjoining owner as a permissive encroachment
It has not been recognized for a sufficient period

Evidence the Surveyor Should Collect

Figure PS.1.36 — Eight-item evidence collection checklist

When investigating potential acquiescence or boundary agreement, the surveyor should document:

Age and condition of fence lines, walls, hedges, and other potential boundary markers
Maintenance patterns -- who maintains which side?
Improvement locations -- are structures built to the fence line?
Cultivation and landscaping patterns
Testimony of owners and neighbors about the history of the fence or line
Aerial photograph history showing the fence or occupation line over time
Prior survey records -- do earlier surveys reference the fence or line?
Tax assessment records -- do they correspond to the fenced area?

Practical Application for Surveyors

When the surveyor discovers that the occupation line (fence, improvements, etc.) differs from the record boundary:

Show both lines on the survey plat -- the record boundary and the occupation line
Note the discrepancy clearly in the survey notes
Document the age and character of the occupation line
Do not render a legal opinion on whether acquiescence has occurred -- that is for the courts
Inform the client that unwritten rights may affect the boundary
Recommend legal counsel when potential unwritten rights are significant

The surveyor's duty is to present the facts clearly so that the client and their attorney can make informed decisions.

Jurisdictional Variations

The requirements for establishing acquiescence and boundary by agreement vary by jurisdiction. The surveyor should be aware of general differences:

Jurisdiction	Time Requirement	Key Distinctions
Most states	Typically the statute of limitations period (5-20 years)	Agreement requires genuine uncertainty; acquiescence requires long recognition
Some western states	May be as short as 5 years	Agreed boundary doctrine is well-established
Eastern states	Varies widely	Many follow the traditional common law requiring the full statutory period
Federal (PLSS)	N/A for government corners	Government survey corners cannot be relocated by private agreement

Boundary by Parol Agreement vs. Deed

A critical distinction exists between a boundary agreement and a land transfer:

A boundary agreement resolves an uncertainty about where an existing boundary lies. It does not transfer land from one party to another -- it clarifies what each party already owns.
A land transfer (even of a small strip) must comply with the Statute of Frauds and requires a written deed, proper consideration, and recording.
Courts scrutinize boundary agreements to ensure they are truly resolving uncertainty rather than disguising a land transfer.

The practical test: If two neighbors know exactly where the boundary is but want to move it for convenience, they need a deed. If two neighbors genuinely do not know where the boundary is and agree on a line, that is a valid boundary agreement.

Common Exam Scenarios

Scenario 1: The Old Fence Two properties share a fence built 50 years ago. A modern survey shows the fence is 4 feet onto Parcel B. Both owners have maintained their respective sides. This is classic acquiescence -- both parties treated the fence as the boundary for well beyond the statutory period.

Scenario 2: The Driveway Agreement Two neighbors disagree about which property a shared driveway is on. They agree to split the driveway at the center and each maintain their half. Ten years later, a survey shows the entire driveway is on one parcel. The boundary by agreement may fix the boundary at the centerline of the driveway because there was genuine uncertainty and the parties agreed and acted upon the agreement.

Scenario 3: The Garage Owner A tells Owner B the boundary is at the fence. Owner B builds a garage to the fence line. The true boundary is actually 3 feet on the other side of the fence. Owner A is estopped from claiming the true boundary because B relied on A's representation and built accordingly.

Scenario 4: Permission Defeats the Claim Owner A tells Owner B: "You can use that strip of land along the fence; I don't need it." Owner B uses the strip for 30 years. Because A gave permission, no acquiescence or prescriptive right can arise, regardless of the duration of use.

Common wrong path — treating every fence as a legal boundary. Fences are ubiquitous on boundary surveys, and not all fences are created equal. Before treating any fence as evidence of acquiescence, ask three questions: (1) Is there genuine uncertainty about the deed boundary? If the deed is clear and the parties know it, acquiescence doesn't arise. (2) Is the recognition mutual? A fence placed by one owner without the other's knowledge or acceptance is unilateral encroachment, not acquiescence. (3) Has it been recognized for the statutory period? A 3-year-old fence, regardless of how clearly it marks occupation, hasn't been in place long enough to invoke the doctrine. Exam questions bait this by describing a prominent old fence and asking whether it is the legal boundary — the correct answer almost always depends on facts beyond the fence's existence (deed clarity, mutual recognition, duration, absence of permission). A fence alone does not move a boundary.

Quick retrieval check — try before reading on.

▶Two neighbors share a hedge that has existed since 1985. The deeds on both sides are unambiguous, and both owners have assessor's tax maps showing the hedge is on Neighbor A's side, 6 ft from the record line. Neighbor A mows both sides of the hedge; Neighbor B maintains only the hedge branches that overhang their side. In 2026, Neighbor A wants to build a fence on the record line. Does acquiescence bar Neighbor A from doing so?

Probably not. Acquiescence requires genuine uncertainty about the boundary — and the fact that both parties have assessor's maps clearly showing the hedge is on A's side (6 ft from the record line) tends to negate uncertainty. If both owners knew all along that the hedge was not the boundary, the 41 years of the hedge's existence don't ripen into acquiescence. Additionally, the maintenance pattern (A mows both sides) suggests A treated the 6-ft strip as their own, not as mutual boundary recognition. Neighbor A is likely free to build the fence on the record line. That said: B could still argue acquiescence if B can produce evidence contradicting the "no uncertainty" conclusion (e.g., an old informal agreement, a prior survey that placed the boundary at the hedge). The surveyor's role is to document the facts — hedge location, age, maintenance patterns, assessor records — and let the parties' attorneys argue the legal conclusion.

Exam Tips

Acquiescence does NOT require hostility -- this is the number one distinction from adverse possession
Both parties must treat the line as the boundary for acquiescence; unilateral encroachment is not acquiescence
Genuine uncertainty is required for boundary by agreement -- parties cannot simply agree to move a clear boundary
Estoppel requires detrimental reliance -- the party must have changed their position based on the representation
A fence that was placed by mutual agreement as the boundary line will likely be upheld even if later surveys show it is not on the "true" line
Practical location by the original surveyor is especially strong evidence of boundary
Permissive use (with the owner's consent) can never ripen into a prescriptive right or acquiescence
The surveyor should show both the record boundary and the occupation line when they differ
On the exam, look for scenarios where two neighbors both treat a fence as the boundary for a long time -- that is acquiescence