Sydney street entertainer Danny Lim has been injured while arrested wearing a sandwich board sign twice found to be cheeky, not criminally offensive.
Chris Murphy on Tuesday shared footage online of the septuagenarian Lim being thrown headfirst into the tiled floors of Sydney's Queen Victoria Building.
A witness can be heard gasping at the sight of Lim's injured face and a small amount of blood on the tiles.
Police handcuffed Lim then reversed the arrest after noticing the injuries, they said.
He was taken by paramedics to St Vincent's Hospital.
"Internal skull damage diagnose(d)," Murphy said on Twitter.
Lim, a former city councillor and regular sight on city streets, was arrested in 2017 and 2019 for the wearable sign that says "SMILE CVN'T! WHY CVN'T?".
He was successful in the courts on both occasions, with a Sydney magistrate in 2019 being highly critical of the behaviour of arresting officers.
Magistrate Jacqueline Milledge said the law was concerned with what would offend the "hypothetical reasonable person", not someone who was "thin-skinned (or) easily offended".
NSW Police said officers arrived at QVB about 11am on Tuesday after Lim declined to leave "when asked".
"Police will allege the man was subsequently issued with a move-on direction by officers and failed to comply," a statement said.
"The man's arrest was discontinued after he struggled with police and sustained an injury to his cheekbone."
Police say they have reviewed body-worn video of the incident.