The US Supreme Court has sided with an Ohio woman who alleged she was discriminated against at her job because she is heterosexual.

The justices voted unanimously in a ruling focused on evidence standards that could make it easier to file similar “reverse discrimination” cases.

Marlean Ames said that despite working for the Ohio Department of Youth Services for more than 20 years, she was denied a promotion and then demoted. She had appealed to the court to challenge the standards required to prove her case.

The decision effectively lowers the burden of proof required for people who are members of a majority group – such as white or heterosexual people – to make discrimination claims.

US court precedent covering some states, including Ohio, had required that members of majority groups show additional “background circumstances” to prove their case or evidence showing a pattern of discrimination.

The court has now ruled that the standard of evidence for a discrimination claim should be the same, regardless of a person’s identity.

The court did not consider Ms Ames’ original discrimination suit.

Ms Ames had said she had positive performance reviews, but a promotion she sought was given to a lesbian. She was then demoted and her job was given to a gay man.

In a lawsuit, she argued her employer had a preference for LGBTQ staff members and denied her opportunities because she identifies as straight. Lower courts ruled that she had failed to provide sufficient evidence of her claim, propelling the burden of proof question to the Supreme Court.

At a February hearing, justices on both sides ideologically appeared sympathetic to her argument.