O'Keefe, 51, appeared in Sydney's Downing Centre Local Court on Monday, where he had assault charges dropped.
Police had alleged O'Keefe choked a 38-year-old woman before he punched and kicked her in a Sydney CBD unit in January 2022.
O'Keefe, a former lawyer and son of former NSW Supreme Court judge Barry O'Keefe, argued he acted in self-defence and pleaded not guilty.
Police prosecutor Michael Cleaver withdrew a number of intentional choking, common assault and assault occasioning bodily harm charges on Monday.
"The prosecution case relies significantly on one single civilian witness who has left the country," Sgt Cleaver told the court.
O'Keefe still faces resisting police, drug possession and domestic violence charges.
He previously avoided a domestic violence conviction in June 2021 after charges were dealt with under the NSW Mental Health Act.
He was granted conditional release in May 2022 to attend a rehabilitation centre for up to 12 months to combat his cocaine, ice and cannabis abuse.
The hearing continues.
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