In France, the period during which third parties can challenge a planning permission only starts when the permit is displayed on site, and that display has to be established: its start date, its continuity, its visibility. Sealway lets you build, right there in the field, photographic evidence timestamped by a qualified third party and verifiable independently.
Built for
Two articles of the French Planning Code (Code de l’urbanisme) and a principle restated by the Conseil d’État, France’s supreme administrative court, set the frame. They place the burden of proving the display on the permit holder.
Notice of the permit, whether express or tacit, or of the prior declaration, must be displayed on the land, visibly from the outside, by the permit holder, from the day the decision is notified or the tacit permission is acquired, and for the whole duration of the works.
The period for third parties to bring a court challenge against a building, development or demolition permit, or a decision not to oppose a prior declaration, runs from the first day of a continuous two-month period of display on the land. Without a compliant display, that period does not run against third parties, subject to the six-month period from completion of the works after which no challenge is admissible (art. R. 600-3).
It is for the holder of a building permit to prove that the display formalities were carried out. Service-Public.fr, the French government’s public information service, adds that in case of a challenge the holder must be able to establish the start date of the display, its continuity, and the legibility and visibility of the board.
A photograph can be evidence. But its date cannot necessarily be established by the file’s metadata alone.
In a decision of 10 March 2025, the Conseil d’État upheld the assessment of an administrative court of appeal which had held that photographs taken by the permit holder, dated by editable digital metadata, did not offer sufficient guarantees of authenticity to establish the display date claimed.
The decision does not say that a photograph is not evidence. It says that metadata, because it can technically be modified, may be found insufficient to establish the date of a photograph.
Conseil d’État · 5th chamber · 10 March 2025
ECLI:FR:CECHS:2025:472387.20250310 · not published in the Lebon reports
To establish that the permit had been displayed on site from a given date, and argue that the challenge brought against it was out of time, the permit holder had produced photographs of the notice board that he had taken himself, arguing that their digital metadata attested to the date they were taken, together with two witness statements. The administrative court of appeal had found these elements insufficient.
Given the technical possibilities of modifying this digital metadata, the court made no error of law in holding that the date of these photographs could not be regarded as offering sufficient guarantees of authenticity.
What Sealway takes from it
An EXIF date is not a qualified timestamp.
Read the decision on the Conseil d’État website (in French) →
The law does not make a report by a commissaire de justice the only admissible proof.
Service-Public.fr states that proof of display can be provided by any means: photographs, statements from witnesses unconnected to the permit holder, or a report drawn up by a commissaire de justice, the French judicial officer formerly known as huissier.
In case of a challenge, the permit holder must be able to establish the start date of the display, its continuity for the whole duration of the works, and the legibility and visibility of the board.
Administrative Court of Appeal of Lyon · 1st chamber · 12 December 2023
The permit holders had deposited five photographs of the notice board in a digital safe whose deposit dates could not be modified. Two years later, a judicial officer recorded the contents of that safe, went to the site to check the geolocation and took new photographs. Together with witness statements, these findings were held sufficient to establish the existence and continuity of the display, even though no report had been drawn up on site at the time of the display.
Proof of the reality, regularity and continuity of the display of the building permit on the land may be provided by the permit holder by any means.
What Sealway takes from it
The court assesses the continuity of the display on the whole file. Digital items whose dates could not be modified were taken into account.
Read the judgment on the Conseil d’État website (in French) →
This judgment does not equate a digital safe, or Sealway, with a report by a commissaire de justice. It shows how the court weighs everything that is produced.
Sealway adds to your photographs what they do not carry by themselves: a date established by a qualified third party, and an integrity anyone can verify.
Three shots from the Sealway app: a wide view placing the board in its surroundings, a view from the public space establishing its visibility from the outside, and a close-up making every mention on the board legible. A video can complete the series. The files are created by the app at the moment of capture.
When the device has a position fix, the geolocation coordinates recorded at capture are written into the file before its fingerprint is computed, along with the device used. They can therefore be part of the evidence. They are context data supplied by the device, not a finding of position by an independent third party.
Sealway computes the SHA-512 cryptographic fingerprint of each file and has the set timestamped by a qualified trust service provider, under the eIDAS Regulation. A qualified electronic timestamp enjoys a presumption of the accuracy of the date and time it indicates and of the integrity of the data it is bound to (Article 41(2)). The date depends neither on the phone’s clock nor on its metadata.
The evidence file gathers the original files, their SHA-512 fingerprints, the qualified timestamp token, the context data, the references of the multi-blockchain anchoring performed for every proof, and what is needed to verify it later without depending on Sealway. The qualified timestamp remains the basis of its probative value; the anchoring complements it. Group the proofs of one project in a collection. Evidence files can be kept in Sealway with a storage subscription, and downloaded into your own archive.
A photograph establishes something at one moment. The continuity of the display is documented by a series of proofs spread over time and consistent with each other.
Wide view, view from the public road, legible board. A Sealway proof as soon as the board goes up.
Same framing, same viewpoint. The board is still in place and legible.
New series. Each proof carries its own date, independent of the previous ones.
New series. If the board is damaged or replaced, document it immediately.
A closing series for the continuous two-month period, then spaced captures until the end of the works, during which the display remains mandatory.
An example of an internal documentation protocol. The regulations do not impose this frequency of captures: they require a continuous display for the whole duration of the works and leave the burden of proving it to the permit holder. A report by a commissaire de justice and statements from witnesses unconnected to the permit holder can complete these elements.
An ordinary photograph remains potential evidence. Sealway adds independent mechanisms that establish its existence and integrity at a given date.
| Criterion | Ordinary photo | Sealway proof |
|---|---|---|
| Original file | Yes | Yes |
| EXIF or device date | Yes | Kept as file metadata |
| Date independent of the phone | No | Qualified electronic timestamp |
| Verifiable integrity | Limited | SHA-512 fingerprint and qualified timestamp |
| Contextual geolocation | Possibly | Can be part of the file, covered by the fingerprint |
| Later verification by a third party | Depends on the file | Evidence file verifiable independently |
The core of a Sealway proof’s evidential value is the qualified electronic timestamp. Blockchain anchoring complements it, for verification.
What Sealway does, and what it does not claim to do.
The texts and decisions cited on this page, linked to their official sources. All are in French.
Sealway does not provide legal advice. These references are given for information; the probative value of the evidence produced is for the court to assess.
Displaying the permit opens a project whose other moments will need documenting too: the condition of the neighbouring properties, the progress of the works, the acceptance.
Photograph and date the condition of a building, a plot or the neighbouring properties before the works start.
Learn more →Build a dated chronology of the state and progress of the site at the important stages, before they are covered up.
Learn more →Document precisely the defects, imperfections or outstanding work at the moment of acceptance, then their lifting.
Learn more →Complete the move-in and move-out état des lieux with photographs whose date and integrity can be verified.
Learn more →Bring together the photographs, their timestamps and the verification material of each project in one evidence file your legal team can rely on.
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