IANAL, but I believe you are technically wrong that it's illegal. Saying more, has however, been used against companies in civil court, with damages awarded, even when the 'more' said was completely accurate.

This is simple misinformation. Most places will only say that much so as to limit unnecessary liability but, in most locales, an entity is not explicitly prohibited from providing additional information with respect to performance, etc.

Right. A typical stealth question that is perfectly allowed is the "would you hire this person again?" question. It says a lot with one yes/no answer.

Exactly. And can sometimes open up follow-ups with, "Can you tell me why not?"

That's not true. Many companies have this as a policy to avoid defamation lawsuits from former employees receiving what they consider a bad reference, but that's not because there's a law forbidding it.

Can you provide a source for this? I've never heard of this before and am curious what legal restriction you are referring to.

It's in a secret section of the constitution on employment law, that overrides the first amendment.

The first amendment (and all the rest of it) has nothing to do with non-governmental, private interactions.

Of course it does, when you're talking about the government regulating non-governmental, private speech, such as this mythical law against employers saying truthfully that you were fired for cause.

Fair point. I suppose I'm really not sure.

That's why companies are free to have this as a company policy.

The First Amendment prevents this policy from being a law.

What would be the purpose of reference checks then?

to verify that you actually worked there. they can also verify that what you put on your resume was your role. Eg I can't really get away with "CEO of Microsoft" from my time as a janitor there.

I should have stated that it depends on the state. Some states may not have these stipulations.

Care to point one out that does?

California, typically one of the hardest on employers, appears to have explicit protection for bad references made based on evidence and without malice. http://www.nolo.com/legal-encyclopedia/california-reference-...

New York's another high-regulation state, and while there's no explicit protection against defamation lawsuits, it's certainly not illegal to invite one via a shitty reference. http://www.nolo.com/legal-encyclopedia/reference-laws-new-yo...

I can't imagine a "no references" law would survive First Amendment muster in the US, regardless of attempted state legislation.