Three categories that must remain distinct
In real estate disputes, classifying the defect is not a matter of terminology. Defects in the thing, absence of promised or essential qualities and delivery of an aliud pro alio are governed by different rules and may lead to different remedies.
When aliud pro alio arises
Italian case law treats aliud pro alio as a radical mismatch: the asset delivered is wholly different in nature, individuality, substance or intended function, or is entirely unfit for the essential economic and social purpose agreed by the parties. The assessment is necessarily fact-specific.
Planning non-compliance and habitability
Planning irregularities do not automatically amount to aliud pro alio. Their legal significance depends on whether they can be cured, whether they prevent lawful use, and whether they undermine the function or marketability that formed the basis of the transaction.
Why classification changes remedies
Ordinary sale warranties are subject to the special rules and time limits governing defects. Aliud pro alio is instead treated as ordinary contractual breach, potentially supporting termination and damages where the statutory requirements are met.
Due diligence before signing
Effective due diligence should address title and planning history, lawful status, use class, habitability, actual dimensions and promised characteristics, potential amnesties and the specific economic purpose of the acquisition.
From defect to strategy
The correct approach is to reconstruct the technical and documentary facts first, then determine whether the issue affects value, a promised quality or the functional identity of the asset itself.