A US federal appeals court says three Seattle police officers were justified when they used a stun gun on a pregnant mother who refused to sign a traffic ticket.

Malaika Brooks was driving her son to school in 2004 when she was stopped for exceeding the speed limit.

The officers used a Taser three times when she refused to get out of her car.

A panel of judges ruled 2-1 the officers were justified in using force because Brooks could have picked her keys up off the floor, started the car and driven away.

The dissenting judge called the ruling absurd saying the officers had no authority to arrest Brooks, let alone use a Taser on a non-threatening woman who was seven months pregnant.

- AAP