I'm adding my suggestion here because as was already noted, it's actually Schutzbaugesetz and not Schutzraumgesetz. Meaning that while the word "shelter" (Schutzraum) does occur in the body of the text, it is not part of the title of this legislation: Gesetz über bauliche Maßnahmen zum Schutz der Zivilbevölkerung (Schutzbaugesetz).

Apparently only Sections 7 and 12 of this legislation are still in force, but if you read the Schutzbaugesetz from the beginning it gives some good clues about what this is all about (and thus how to translate the title). Basically, it says (very loosely translated) that

1. Shelters must be constructed and other structural precautions implemented to supplement the civilian population's own self-defense mechanisms and to protect systems and installations vital to survival and defense efforts.

(1) Zur Ergänzung des Selbstschutzes der Zivilbevölkerung sowie zum Schutz Lebens- und verteidigungswichtiger Anlagen und Einrichtungen sind
Schutzräume zu schaffen und andere bauliche Vorkehrungen zu treffen.

And then it goes on to talk about the requirements applicable to builders as well as project financing.

I've suggested writing out the long form here because otherwise it's going to be pretty unclear what this is about. And "Construction of [Protective Structures] Act" (or whatever one chooses for "Schutz") isn't a whole lot shorter.

A more literal option could also be "Act on structural measures designed to [defend/protect] the civilian population" or the like.

However, the OP might want to give the points the person who found the correct name of this legislation as that was really the key here.