Can a player with a suspected concussion come back on later in the same match?

Not without clearance from a medical professional. The Hockey Australia Concussion Policy (effective 1 January 2024) says that at club and state matches there may be no medical professional at the venue, and that without assessment and clearance by a qualified medical professional, a player with a concussion or suspected concussion must not return to play, training or activity on the same day. Its slogan is "If in doubt, sit them out!"

Where no dedicated match-day medical professional is present, the policy says that under no circumstances should a removed player be allowed to resume the match. The only exception it gives is a player removed for the "needs further assessment" signs (a facial or head injury, lying motionless for over two seconds, headache, blurred vision, balance problems or dizziness, nausea, or "not quite right"), who may return if a medical professional acting in a dedicated match-day role assesses and clears them of concussion.