Is true that giving bad references of someone is illegal? ?

They aren't allowed to lie, but they are allowed to point out all your flaws.

No. And even if it was, your situation wouldn't be any better. Because if it was illegal to give a bad reference, then when someone called and didn't get a good reference (meaning that the person they called didn't give a good or bad reference because it was illegal to give a bad one), that would hurt you as much as a bad one.

No, not illegal if what she says is true. And from what you say, she is not likely the reason anyway you are not being hired.

Why would giving an opinion about you be illegal? Of course it is not illegal. References are a MUST at any and all job applications/interviews.

If you have been a bad employee then they can state the facts but they have to be the truth.

Any question 'is it illegal' depends on the local laws where you live which you have given no indication.

At your next interview, mention (BRIEFLY!) that she didn't like you and never followed up/acknowledged your good work.That way, the person calling won't be caught by surprise and might even see your old boss for the ***** that she is! 

Unless she is saying something actually damaging about you, it's not illegal. It's also not illegal to lie about it, unfortunately. 


If she is stating something untrue, or something that will harm your standing or reputation, or actively trying to get you fired by stating things that are not true about you, then you  may have a case for slander. But in order to prove it, you'll have to have proof of what she actually SAID. That's very difficult to get. 


First thing you should do is to put on your resume or new job application that prospective employers should NOT contact this particular person. Instead, you can get written letters from co-workers or other supervisors for references. 


You must explain to your prospective new employer that there is a hostile relationship between you and this former supervisor, and that you will not get a good reference from her despite having had no issues with duties or the work involved. You cannot say anything BAD about HER. Just that there will not be good references. 

False...............
Maybe you need to work on your resume.

It is commonly assumed that a previous employer must give a reference and is legally prohibited from giving a bad one. This is not the case. Your employer can give you a bad or unfavourable reference, but only if they genuinely believe it to be true and accurate and have reasonable grounds for that belief. If it's wrong technically you could sue for defamation but that's so expensive.