It's illegal in the US for the company or anyone representing the company to say anything more than that they worked for the company, and what they worked on.

They can't tell the person that the employee was fired, or anything like that.

But as noted - there are ways used to get around such things (that is, the laws of our country). Those laws exist because people were wrongly discriminated against by using such "references".

But if you have a reference to someone you worked with, and they are no longer employed by that company - then I'm pretty sure they can answer anything they wanted too (unless there's some kind of NDA they are still under after leaving the company). Because they don't represent the employer any longer, and are a personal reference - things become more casual.