Jaja, das gute, alte rechtsenglische "shall"... Man kann schon den Eindruck bekommen, die gesetzeformulierenden Juristen verwendeten solche Begriffe vorsätzlich zur Verwirrung aller "Uneingeweihten".
Auch wenn man wohl in unserem Fall eindeutig von "shall = muss" ausgehen kann, ist die Verwendung des Wortes im juristischen Kontext nicht immer ganz eindeutig und sauber definiert. Dazu:
“Shall” isn’t plain English. . . But legal drafters use “shall” incessantly. They learn it by osmosis in law school, and the lesson is fortified in law practice.
Ask a drafter what “shall” means, and you’ll hear that it’s a mandatory word—opposed to the permissive “may”. Although this isn’t a lie, it’s a gross inaccuracy. . . Often, it’s true, “shall” is mandatory. . . Yet the word frequently bears other meanings—sometimes even masquerading as a synonym of “may”. . . In just about every jurisdiction, courts have held that “shall” can mean not just “must” and “may”, but also “will” and “is”. Increasingly, official drafting bodies are recognizing the problem. . .Many . . drafters have adopted the “shall-less” style. . . You should do the same.
Bryan Garner, Legal Writing in Plain English, 2001, pp 105-06.
Aus: https://www.plainlanguage.gov/howto/wordsuggestions/shallmust.cfm
Faszinierend, zu welchen interessanten Diskussionen Björns europäische Transkontinentalflüge führen ;-)