Principle of Proportionality in Construction Works: Balancing Legality and Reason

When discussing urban planning supervision and measures to restore legality in irregular works, a key question often arises: how far can public authorities go in enforcing compliance? Can a Municipal Council order the demolition of an irregular construction without considering less severe alternatives? In this context, the principle of proportionality plays a central role in Portuguese planning law, acting as a safeguard against arbitrary administrative power and ensuring balance between the public interest and individual rights.

This article explains, in clear terms, what the principle of proportionality is, how it applies to building works, its legal basis within the Legal Framework for Urbanisation and Building (RJUE), and its practical implications for property owners, technical professionals, and public authorities.

Annex after approved municipal legalisation

What is the Principle of Proportionality?

The principle of proportionality is a core doctrine of administrative law that governs all public administration activity. It is enshrined in Article 266(2) of the Portuguese Constitution, which states that administrative bodies and agents “are subject to the Constitution and the law, and must act in accordance with the principles of equality, proportionality, justice, impartiality and good faith.”

In the field of urban planning and building, this principle requires that measures adopted by public authorities to enforce urban legality must be suitable, necessary, and proportionate to the goals they seek to achieve. In practical terms, the Municipality cannot “use a cannon to kill a fly.” If a less onerous measure can restore legality, that solution must take precedence.

The Principle of Proportionality in the RJUE

Under the RJUE (Decree‑Law No. 555/99, of 16 December), the principle of proportionality is explicitly linked to urban legality enforcement and restoration actions.

Article 102 – Restoration of Urban Legality

Authorities must adopt any measures necessary to restore legality when unlawful works have been carried out, such as:

• Works lacking prior permission or communication.

• Works inconsistent with approved plans.

• Works under revoked or null authorisations.

• Works breaching applicable legal or regulatory standards.

Available measures include: suspension, corrective works, legalisation, partial or total demolition, and restoration of the site. These measures follow an implicit hierarchy: corrective actions and legalisation come before demolition — a direct reflection of proportionality.

Demolition as a Measure of Last Resort

Courts have consistently held that demolition should only occur once the possibility of legalisation has been examined. Therefore, a Municipality cannot order demolition without first:

1. Assessing whether legalisation is possible.

2. Notifying the owner to apply for it within a set timeframe.

3. Evaluating whether the existing work poses significant public interest risks justifying immediate removal.

"Only after confirming legalisation is impossible or the owner fails to act may demolition be ordered."

Example:

A homeowner builds an unauthorised annex. The Municipality detects it and requests a legalisation proposal.

• If the annex complies with planning rules, the owner submits a project and the council approves it.

• If it breaches mandatory standards severely, demolition or corrective works follow.

• If the owner ignores the notice, demolition can be ordered after due process.

Legalisation as a Legality Restoration Tool

With Decree‑Law No. 136/2014, the RJUE expressly recognised legalisation as a way to restore compliance. This legislative change acknowledged that indiscriminate demolition of the many informal constructions in Portugal would be disproportionate, economically unfeasible, socially damaging, and environmentally unsustainable.

Article 102‑A of the RJUE – Legalisation

If unauthorised works can be brought into conformity with current regulations — through modifications if needed — the Municipality must invite the owner to legalise them within a fixed period. Failure to comply may lead to compulsory legalisation by the council or demolition.

When Proportionality Yields

Immediate demolition is justified in rare cases:

• Imminent danger: where the structure poses risk to public safety or health.

• Irreparable structural illegality: such as being built in non‑construction zones or severely breaching mandatory safety or zoning standards.

• Owner inaction: persistent refusal or failure to regularise after notification.

Dimensions of Proportionality

The principle divides into three interrelated sub‑principles:

1. Suitability: The measure must effectively restore legality.

2. Necessity: From several effective options, the least burdensome must be chosen.

3. Proportionality stricto sensu: The sacrifice imposed must be in fair balance with the public benefit achieved.

View of the neighbouring plot of the approved annex

Administrative Responsibility

Applying proportionality correctly has real consequences:

• Duty to provide justification: Demolition decisions must explain why legalisation is impossible and how demolition meets legal, necessary, and proportional criteria.

• Right to prior hearing: Property owners must be heard before any destructive measure is taken.

• Civil liability: Disproportionate measures — such as demolishing a building that could have been legalised — may result in administrative liability and owner compensation.

Proportionality in Supervision

Municipal oversight must be effective but not excessive. Recent reforms (Decree‑Law No. 10/2024) strengthened post‑construction inspection while simplifying prior control. This means enforcement should be risk‑based and remain proportional — targeting serious infringements without stifling legitimate building activity.

Practical Advice

For property owners:

• Never build without proper authorisation.

• If irregularities exist, act quickly and seek technical support for legalisation.

• Respond to municipal notices and keep all documentation well organised.

Final considerations

The principle of proportionality is fundamental to the rule of law and especially important in urban management, where conflicting interests — legality, property rights, housing needs, and environmental protection — must be weighed carefully. Demolition is not a routine act; it destroys assets, disrupts lives, and creates social and environmental costs. Hence, legislation and court rulings require it as ultima ratio, a last resort, only when legalisation is objectively impossible or unjustifiably neglected.

Restoring legality should be intelligent, balanced, and proportionate — correcting irregularities without excess harm. For citizens, compliance is always the best path; for authorities, proportionality ensures fair, transparent, and lawful urban governance that respects both public interest and human dignity.