The mother of a baby murdered in Western Australia's north has been given a suspended prison sentence for assaulting police the night her son was taken, with the magistrate saying "I just can't jail her".

In March 2013 Tamica Anne Mullaley's 10-month-old son Charlie was taken, tortured and killed by her then-partner Mervyn Bell.

Prior to taking baby Charlie, he assaulted Mullaley, breaking her collar bone, ribs and damaging her spleen and kidney.

Bell was serving a life sentence for the murder, and five years for the assault of Mullaley until he killed himself in his prison cell in September.

Police laid charges relating to the night they were called to assist Mullaley after she had been assaulted.

When they arrived, Mullaley was dressed only in a bloodied sheet and was acting aggressively.

At the time they were not aware of the seriousness of her injuries.

Mervyn Bell was sentenced to life for murdering Charlie Mullaley. He was found dead in his prison cell in September.

She kicked one officer in the chest and spat at the other officer, and was consequently charged with two counts of assaulting a public officer and one count of obstructing officers.

Mullaley was admitted to hospital that night and it was while she was in hospital that Bell took Charlie.

At a trial in the Broome Magistrates court in September, Mullaley was convicted of all three charges.

Yesterday she was given a 12-month prison sentence, suspended for a further 12 months.

She was also fined a total of $900 for unrelated stealing and assault offences.

'I just can't jail her with what she's gone through'

In sentencing, Magistrate Stephen Sharratt said although he considered assaulting public officers a very serious offence, he appreciated Mullaley had just been badly assaulted.

"What happened to her made a great deal of difference to the way she reacted to their [the police] presence. Those wounds would have killed her without medical intervention," he said.

Mr Sharratt acknowledged that while unrelated, the stealing and assault charges occurred in a period Mullaley was grieving and was in and out of hospital seeking treatment for ongoing complications from the wounds inflicted by Bell.

"She's gone understandably awry ... spent months in hospital. I just can't jail her [Ms Mullaley] with what she's gone through," he said.

"If ever there was a time for the court to be merciful, it's this matter today."

Outside the court, Mullaley said she was relieved and pleased with the outcome.

"I'm really happy. It's over and the outcome was really good. I was quite frightened of getting imprisoned," she said.

"I'm very thankful to Mr Sharratt for recognising what had happened within all that time."