A teenager who punched an unsuspecting woman in the back of the head has escaped time behind bars as the magistrate says she would be a 'victim in jail'.

Tannah Knight-Olsen, from Sydney's Barden Ridge, appeared in court this week for breaching her bond conditions over the 2017 assault where she bashed an unsuspecting patron at the Miranda Hotel.

Knight-Olsen was allegedly caught with the drugs ice and cannabis earlier this year - which contravened her bond conditions, The Daily Telegraph reported.

Tannah Knight-Olsen (pictured) from Sydney's Barden Ridge appeared in court this week for breaching her bond conditions over the 2017 assault where she bashed an unsuspecting patron at the Miranda Hotel

Tannah Knight-Olsen was allegedly caught with the drug ice and cannabis earlier this year - which goes against her good behaviour bond

She was charged with possessing 0.37g of marijuana on May 30. She was also charged with possessing 0.19g of ice on July 24.

She has also faced violence charges, including incidents where she smashed a landline phone and a pot plant during disputes with family members - which she pleaded guilty to.

During sentencing, Sutherland Court magistrate Glenn Walsh said Knight-Olsen needed to break the cycle of her bad behaviour.

'Whilst I understand that you’re looking for something in life that eases your pain, (the drug use) makes you a worse person.

'She needs assistance and she needs that in the community - she'd just be a victim in jail.'

The 19-year-old was sentenced to 12 months imprisonment, to be served in the community.