The US Supreme Court grappled last week with how to determine if an employer had unlawfully retaliated against a worker because she claimed sexual harassment or other discrimination.

In the case of Burlington Northern v White, former forklift operator Sheila White claimed she was transferred to a lesser job after complaining to the company about sexual harassment, USA Today reported.

After White was hired to work in Burlington Northern's train yards in 1997, she complained about sexual harassment. Her boss was suspended for 10 days but she was transferred to a dirtier railway track labourer job. A few months later, she was suspended for 37 days without pay after the company reviewed her complaint.

White alleged the actions were unlawful retaliation under the US Civil Rights Act and a jury awarded her USD43,000 in damages. The verdict was upheld by the US Court of Appeals for the 6th Circuit. Burlington Northern is now appealing.

Burlington Northern claims the standard currently used by the lower court "dramatically expands" employer liability under federal anti-bias law.

Burlington Northern's legal representative Carter Phillips said a lenient standard would interfere with how companies managed their businesses. He said "adverse" actions should primarily concern changes in pay.

White's legal representative Donald Donati said if workers were not broadly protected from retaliation, bias victims were unlikely to come forward.

A court ruling is expected in July.