There actually probably is a law where you live, but in almost all jurisdictions I don't think it's enforced. Parts of Canada were trying to protect the title Software Engineer but I think even they've given up now. It's unfortunately because now the title doesn't really mean anything.
I'm from Quebec, there's no laws that surround specifically software engineer. There's some for engineers in general, but nothing surrounding software development. The title truly doesn't means anything for us as long as no laws are passed, which is why I don't pay for it either.
I think Microsoft won on appeal, but I can't find anything on that right now.
I hate repeating myself, but here again: there's no laws that surround specifically software engineer.
I'm not arguing they doesn't have good laws around the engineer title, I even mention that I can't use the title of engineer because I don't pay for it. What I'm arguing is that there's no laws that surround specifically software engineer.
That title is meaningless and doesn't give us any power over our own works. It doesn't protect our works, thus it doesn't allow us to takes responsibility over it. In the case of the Therac 25, the software was done for the previous hardware and reused over the newer one. Even if the software engineer was against doing that, there's nothing in his power to stop that. I don't know if the electrical engineer has more power and could have done it in the Therac 25 situation, but as far as I know, only civil engineers require signature over their works to proceed.