Negative Verification

What can a person do if his ex employer has given him clear relieving letter but when the same is verified by the persons new employer they give him negative feedback?

There is nothing you can do, unless the feedback is false and clearly verifiable as false (like denying you were working there).
Think logically, what will you do ?
Get a court order for him to say nice things about you ?

The same topic had been discussed some time back too. You will get quite a few options when you refer the thread : https://www.citehr.com/453395-negati...check-pg2.html

If the negative Reference Check is given in writing then its bad luck on employees' part but if its only verbal, then a relieving letter in its written format is always a better tool for verifying employees' clear background status.

Dear Sadiq,
There is nothing to worry my dear. You are relieved from your duty from your previous employer and you have the documents. During verification check many third party company send scan copy of all employment documents. Your previous employer has to validate the documents; is forced to do if they are true.
Regarding feedback if documents are validated and there is probability of 50:50 that may receive negative feedback. Nothing to worry.

I am in similar situation, All documents were authentic but the ex-comp HR is reluctant to verify. He is saying he do not provide any reference as the employe has broken NDA, actually there was no NDA or any agreement that was broken, employee joined the client company after proper reliving.
https://www.citehr.com/462525-after-...g-relived.html
What to do in this case when HR says he do not provide information regarding the same.