The teenager's family alleged police used excessive force during her arrest. Further details of the teenager and the arrest are withheld to protect her identity.
Police said a review of body-worn camera footage found the officers acted within policy.
The girl was then taken to a hospital for an undisclosed health issue in the custody of the Department of Justice. A justice department spokesperson said it could not comment on the specific case but that restraints are used "as part of standard custodial management practices" for anyone in custody in an unsecured medical facility. They noted that medical practitioners can request modifications where clinically necessary and that the measures are in place to ensure safety.
Critics condemned the practice. Noongar advocate Mervyn Eades called the use of shackles an "abomination". "We're talking about a child, not a serious criminal," he said, linking the image of chains to colonisation. Debbie Kilroy of the National Network said the incident shows why federal regulation is needed. She said the teenager needed care rather than being chained down.
The case comes amid growing pressure on Australian governments to end shackling in hospital settings. Victorian senator Lidia Thorpe recently introduced federal legislation to ban shackling women during childbirth and stop the strip-searching of children, but the bill was blocked by Labor and the Coalition, who said the issue falls to state governments. Days later, an incarcerated Indigenous woman was shackled to a hospital bed in Queensland while in labour.