CANBERRA, July 2 -- In an Australian psychedelic-assisted therapy session, the person most responsible for what happens if a patient's mind goes somewhere dangerous can now walk out partway through. That is the practical effect of a rule change from the Therapeutic Goods Administration, and it has split the clinicians who run the country's world-first program roughly down the middle.

Since 2023, Australia has allowed authorised psychiatrists to prescribe MDMA for post-traumatic stress disorder and psilocybin for treatment-resistant depression, the first national regulatory pathway of its kind anywhere in the world. Under the original rules, the prescribing psychiatrist had to remain physically present for the entire session, from the mom...