Luxembourg and Germany share a border unlike any other in Europe, where the Moselle, Sauer, and Our rivers are governed jointly by the two nations rather than split by a traditional border line. This unique arrangement, known as the German-Luxembourgish condominium, places the rivers, their islands, and certain bridges under shared sovereignty. The origins of this system date back to the Congress of Vienna in 1815, a historical moment when European powers redefined borders following the Napoleonic Wars.
Article 25 of the Final Act of the Congress of Vienna established that these rivers would be under joint ownership, deviating from the typical practice of dividing them along a median line. Subsequent treaties signed in Aachen in 1816 between the Netherlands, which at the time governed Luxembourg, and Prussia, solidified this arrangement. As Luxembourg eventually gained independence and Prussia became part of the German Empire, the rights and agreements set in the 19th century were preserved. Consequently, the current German-Luxembourgish border largely mirrors the historical delineation.
For over a century, the status of bridges crossing these shared rivers remained ambiguous. It wasn’t until negotiations following the canalisation of the Moselle in 1979 that clarity was sought. The issue was formally addressed with the signing of a border treaty in 1984, which included bridges and footbridges within the shared territory. Today, the condominium operates under a system of concurrent jurisdiction, allowing both German and Luxembourgish laws to apply, with bilateral agreements in place to manage any conflicts that might arise.
Law enforcement from both countries is permitted to operate within this shared territory, including conducting joint patrols. Officers from either nation can intervene in incidents occurring on the shared rivers or bridges, with jurisdiction over legal proceedings determined by factors such as the individuals involved and the circumstances surrounding the offense. This arrangement is one of the rare examples of shared sovereignty in Europe, offering a distinctive model of border management that contrasts with the more conventional boundaries seen between most countries.