Landscaping your garden is not without risks

My neighbour has built a shed in his garden that requires planning permission. Apparently, he never applied for permission. After some heated exchanges with the authorities following a report, nothing has happened for a long time. I wonder whether the passage of time can benefit my neighbour and whether the same would apply to my slightly improvised swimming pool, which is also in an agricultural zone...
JM, Satigny

The passage of time does not always erase irregularities, especially when it comes to building without planning permission.
Under Swiss law, a major distinction is made between buildings located in building zones and those located outside them, particularly in agricultural zones. For decades, the case law of the Swiss Federal Supreme Court has recognised a form of "prescription" in building zones: if no authority has required restoration within this period, it generally loses the right to do so in order to guarantee legal certainty. This statute of limitations, based on Federal Court case law, applies in principle only in building zones. However, the absence of a clear ruling on the subject had left the question open as to its application in agricultural zones.
Our Supreme Court recently clarified the situation: the prescription does not apply to buildings located in agricultural or non-building zones. The federal judges noted that these zones have been governed by strict standards for many years, leaving the cantons little room for interpretation. It is therefore easy to determine whether or not a building is compliant, even after several decades. Consequently, even after thirty years, an authority can order the demolition of a structure illegally erected outside the building zone.
So it all depends on the location of your neighbour's shed and your swimming pool. If your neighbour's hut is located in a building zone and has remained untouched and tolerated for more than thirty years, it could possibly benefit from this prescription. But if the shed is new or located in an agricultural zone, it is unlikely that the simple passage of time will protect your neighbour from having to restore it.
As for your swimming pool in an agricultural zone, the law is even stricter in this respect. Current case law leaves no room for a similar prescription. Even after several decades, the authorities can require it to be dismantled if it was built without valid special authorisation, unless you can demonstrate an acquired right or original legality, which is rare.
In agricultural areas, those who improvise themselves as builders can find themselves in trouble, and time is not on their side...