Comment ça se fait que quelqu'un qui a juste pris la terre sous un bâtiment peut aussi se retrouver propriétaire des étages au-dessus sans jamais les avoir utilisés ?
Consequences

In 2008, due to the volume of adverse possession and boundary dispute cases throughout New York City, the New York State Legislature amended and limited the ability of land to be acquired by adverse possession. Prior to the 2008 amendment, to acquire property by adverse possession, all that was required was a showing that the possession constituted an actual invasion of or infringement upon the owner's rights. Approximately eight years after the 2008 amendment, on 30 June 2016, the New York State Appellate Division, First Department (i.e., the appellate court covering the territory of Manhattan) determined the legal questions concerning the scope of rights acquired by adverse possession and how the First Department would treat claims of adverse possession where title had vested prior to 2008. The Court specifically held that title to the adversely possessed property vested when the plaintiff "satisfie the requirement of the statute in effect at the relevant time." In other words, if title had vested at some time "after" the 2008 amendment, a plaintiff would have to satisfy the adverse possession standards amended by the New York State Legislature in 2008; however, if title vested at some time "before" the 2008 amendment, a plaintiff would have lawfully acquired title to the disputed area by satisfying the pre-amendment standard for adverse possession. Hudson Square Hotel also resolved two often highly litigated issues in adverse possession cases where the air rights are more valuable than the underlying land itself: (a) "where" (i.e., in three-dimensional physical space) is an encroachment required in order for such encroachment to have any relevant operative effect or consequences under the law of adverse possession, and (b) "what" property rights are acquired as a result of title to the ground floor area (i.e., the land) vesting with the plaintiff. In Hudson Square Hotel the defendant argued that the plaintiff had only acquired title to the underlying land, but not the air rights, because the plaintiff never encroached above the two-story building. This argument was motivated, in part, by the fact that the zoning laws at the time permitted the owner of the land to build (i.e., develop) up to six times the square footage of the ground floor area. For example, if the disputed area was 1,000 square feet, there would be 6,000 square feet of buildable square footage to potentially be won or lost by adverse possession. The Court clarified, "It is the encroachment on the land... that allows title to pass to the adverse possessor." In other words, the plaintiff did not need to encroach upon all six stories in order to adversely possess the air rights above the land. The Court also held, "With title to land come air rights." In other words, by acquiring title to the land (i.e., ground floor area), the plaintiff also acquired ownership of the more valuable air rights that were derivative of title to the underlying land.
Origines

Le terrain a également, dans son sens juridique, une étendue indéfinie, à la fois vers le haut et vers le bas. *Cujus est solum, ejus est usque ad coelum* est la maxime du droit, en ce qui concerne la hauteur ; par conséquent, aucun homme ne peut ériger aucun bâtiment, ou autre chose, de manière à surplomber le terrain d'un autre. Et, vers le bas, tout ce qui se trouve sur une ligne droite entre la surface d'un terrain et le centre de la terre appartient au propriétaire de la surface ; comme l'expérience quotidienne le démontre dans les pays miniers. Ainsi, le mot « terrain » comprend non seulement la surface de la terre, mais tout ce qui se trouve en dessous ou au-dessus. Par conséquent, si un homme cède tous ses terrains, il cède par là tous ses mines de métaux et autres fossiles, ses forêts, ses eaux et ses maisons, ainsi que ses champs et ses prairies.
### Query ###
Comment ça se fait que quelqu'un qui a juste pris la terre sous un bâtiment peut aussi se retrouver propriétaire des étages au-dessus sans jamais les avoir utilisés ?

### Main Text ###
Consequences

In 2008, due to the volume of adverse possession and boundary dispute cases throughout New York City, the New York State Legislature amended and limited the ability of land to be acquired by adverse possession. Prior to the 2008 amendment, to acquire property by adverse possession, all that was required was a showing that the possession constituted an actual invasion of or infringement upon the owner's rights. Approximately eight years after the 2008 amendment, on 30 June 2016, the New York State Appellate Division, First Department (i.e., the appellate court covering the territory of Manhattan) determined the legal questions concerning the scope of rights acquired by adverse possession and how the First Department would treat claims of adverse possession where title had vested prior to 2008. The Court specifically held that title to the adversely possessed property vested when the plaintiff "satisfie the requirement of the statute in effect at the relevant time." In other words, if title had vested at some time "after" the 2008 amendment, a plaintiff would have to satisfy the adverse possession standards amended by the New York State Legislature in 2008; however, if title vested at some time "before" the 2008 amendment, a plaintiff would have lawfully acquired title to the disputed area by satisfying the pre-amendment standard for adverse possession. Hudson Square Hotel also resolved two often highly litigated issues in adverse possession cases where the air rights are more valuable than the underlying land itself: (a) "where" (i.e., in three-dimensional physical space) is an encroachment required in order for such encroachment to have any relevant operative effect or consequences under the law of adverse possession, and (b) "what" property rights are acquired as a result of title to the ground floor area (i.e., the land) vesting with the plaintiff. In Hudson Square Hotel the defendant argued that the plaintiff had only acquired title to the underlying land, but not the air rights, because the plaintiff never encroached above the two-story building. This argument was motivated, in part, by the fact that the zoning laws at the time permitted the owner of the land to build (i.e., develop) up to six times the square footage of the ground floor area. For example, if the disputed area was 1,000 square feet, there would be 6,000 square feet of buildable square footage to potentially be won or lost by adverse possession. The Court clarified, "It is the encroachment on the land... that allows title to pass to the adverse possessor." In other words, the plaintiff did not need to encroach upon all six stories in order to adversely possess the air rights above the land. The Court also held, "With title to land come air rights." In other words, by acquiring title to the land (i.e., ground floor area), the plaintiff also acquired ownership of the more valuable air rights that were derivative of title to the underlying land.

### Supplementary Text ###
Origines

Le terrain a également, dans son sens juridique, une étendue indéfinie, à la fois vers le haut et vers le bas. *Cujus est solum, ejus est usque ad coelum* est la maxime du droit, en ce qui concerne la hauteur ; par conséquent, aucun homme ne peut ériger aucun bâtiment, ou autre chose, de manière à surplomber le terrain d'un autre. Et, vers le bas, tout ce qui se trouve sur une ligne droite entre la surface d'un terrain et le centre de la terre appartient au propriétaire de la surface ; comme l'expérience quotidienne le démontre dans les pays miniers. Ainsi, le mot « terrain » comprend non seulement la surface de la terre, mais tout ce qui se trouve en dessous ou au-dessus. Par conséquent, si un homme cède tous ses terrains, il cède par là tous ses mines de métaux et autres fossiles, ses forêts, ses eaux et ses maisons, ainsi que ses champs et ses prairies.

### Draft ###

### 1. Query Parsing

"Comment ça se fait que quelqu'un qui a juste pris la terre sous un bâtiment peut aussi se retrouver propriétaire des étages au-dessus sans jamais les avoir utilisés?"

→ Core confusion: acquiring unused upper floors through ground-level possession.

Translation issues: "juste pris" = "just took" suggests squatting, but legal context broader.

! Key insight needed: French civil law vs. common law property concepts.

### 2. Legal Framework Analysis

Two distinct legal principles at play:

**Adverse possession** (French: "acquisition par prescription")
- Physical occupation of land
- Continuous, exclusive, hostile possession
- Time requirements vary by jurisdiction
- ● High confidence: ground-level occupation can transfer title

**Vertical property rights** (French: "droits de superficie")
- Cujus est solum, ejus est usque ad coelum principle
- Owner of land owns to infinity upward
- ◐ Partial: airspace rights subject to reasonableness limits

### 3. Logical Chain Resolution

Ground-level possessor acquires:
```
Physical control → Legal title (adverse possession)
     ↓
Bundle of rights transfers:
     ├─ surface ownership
     └─ [inherent] vertical air rights
```

! Critical point: air rights don't need separate acquisition.

### 4. Jurisdictional Context

French civil law approach:
- ● All property rights transfer with land ownership
- Caveat: building height restrictions, servitude rights
- ∴ Ground owner automatically controls vertical space

Common law comparison:
- Separate airspace ownership concepts
- Could theoretically have ground + air rights division

### 5. Practical Constraints

⚠ Legal complexity varies by jurisdiction
⚠ Building codes limit vertical development rights
⚠ Servitudes, easements affect airspace use

**Physical realism check**: ✓
- Ground-level presence enables legal control
- Vertical space naturally follows horizontal ownership
- Economic incentives align (development potential)

### 6. Synthesis

User's confusion stems from:
- Separating vertical elements artificially
- Not recognizing inherent property bundle transfer
- Underestimating legal completeness of ground ownership

**Answer framework**:
1. Adverse possession mechanics transfer full title
2. Vertical property rights principle makes air space ownership automatic
3. Practical examples demonstrate economic significance
4. Jurisdictional variations exist but core principle stable

→ Resolution: Legal system treats ground + air as unified property unit. Physical occupation of ground triggers complete ownership transfer including unused vertical space.

### Answer###
Votre question touche à un principe fondamental du droit immobilier : le propriétaire d'un terrain détient par défaut tous les droits au-dessus et en dessous de ce terrain. Cette règle s'appuie sur le principe juridique selon lequel "celui qui possède le sol possède jusqu'au ciel" (cujus est solum, ejus est usque ad coelum).

Dans le cadre du droit français, lorsque quelqu'un occupe physiquement une parcelle de terrain de manière continue et exclusive, il peut théoriquement acquérir la propriété de cette terre par prescription acquisitive (l'équivalent de l'adverse possession en common law). L'important est que cette occupation soit réelle, publique et non-consentante.

Mais ici se pose une question cruciale : l'acquisition par prescription ne concerne que les droits réels sur le terrain lui-même. Le principe fondamental demeure que les droits de propriété suivent naturellement la possession du sol. Ainsi, lorsque le terrain est acquis par ce mécanisme, tous les droits qui y sont attachés se transmettent automatiquement : les droits de superficie aérienne font partie intégrante de la propriété foncière.

En d'autres termes, le propriétaire du terrain devient ipso facto propriétaire de l'espace aérien au-dessus de ce terrain, même s'il n'a jamais construit ou utilisé cet espace vertical. Les droits de construction et les potentialités d'aménagement du terrain suivent donc automatiquement le transfert de propriété du sol.

Cette situation peut effectivement créer des dynamiques complexes, notamment lorsque la valeur des droits de construction en hauteur dépasse largement celle du terrain lui-même.