She will leave the service at the end of June.
Barnard and the union are currently awaiting the Constitutional Court’s judgment on a police bid to appeal a Supreme Court of Appeal (SCA) decision in November last year.
The SCA overturned a Labour Appeal Court ruling that the police were correct in not promoting Barnard because she is white.
The application was heard on March 20. Acting Chief Justice Dikgang Moseneke reserved judgment.
“Her resignation from the police has no impact upon the case at all,” Solidarity deputy general secretary Dirk Hermann said.
It was understood Barnard would work in the private sector.
She twice applied unsuccessfully for promotion to superintendent within the police’s National Evaluation Services, which deals with the public’s complaints about the police’s service.
Despite recommendations by an interview panel and her divisional commissioner, the national police commissioner did not appoint her to the position. He said it would negatively affect racial representivity at the level of superintendent.
“She experienced more and more in the past couple of months a clash of value systems between herself and the police,” said Hermann.
“She quite strongly believes what she is fighting for is right in a constitutional South Africa, but the continuous efforts by the police to oppose her actions in court is of course very disappointing to her.”
Hermann hoped her resignation would cause the police to reflect.
“I hope this is a mirror for the police because if someone passionate like Renate resigns from the police, it’s a message that something is wrong in the police.
“On behalf of the public of South Africa, I can say it must be very disappointed in the fact that she resigned because the public lost a very loyal and passionate police officer.
“I think she’s done a lot to inspire South Africans to fight for what she believes is right. This is a nine-year fight and this led to her resigning from the police, which is very unfortunate.”
The matter was first heard in the Labour Court, which ruled in favour of Barnard. The police appealed the ruling in the Labour Appeal Court, which ruled in its favour.
Solidarity and Barnard then approached the SCA.