> unless you can read minds, it'd be hard to prove

That's not how it works.

There is going to be an evidentiary standard (such as "preponderance of the evidence" -- it won't be "beyond a reasonable doubt") applied by an administrative law judge.

The judge can very well decide he CAN read minds -- unless YOU can read minds, or he decides to tell you, you won't know.

Can't the company be compelled to provide salary data for the role? I assume there is some kind of enforcement mechanism. So then it's a matter of explaining why your lowest paid senior engineer makes 150k, the median makes 200k and you've listed a floor of 10k? The judge/jury don't have to accept a smarmy response about how the hypothetical candidate might conceivably make 10k.

And on the subject of the window, most places have much narrower bands than that for a role. It might be that wide for all engineers, but not for senior engineers for example.

For software engineering compensation, wide salary range isn't the biggest issue. It's that much of the compensation (often 25% to 60%) isn't salary: it's stock and discretionary bonus.

I haven't read the background for this law, but I guess it's meant to help people earning less than $100k, and people with less power to negotiate an initial offer.