Sydney resident Leeza Tracey Ormsby, 37, was arrested in a drug raid on February 12.
Her lawyer, Ari Soenardi, says his client had only gone to the raided villa to pick up her laptop and towel and is not connected to the drugs police found inside.
The Paddington resident admits she had marijuana in her handbag, but Mr Soenardi says police are determined to link her to the hashish and MDMA found inside.
They have had Ormsby in custody without charge since her arrest, and will likely extend her detention on Tuesday for at least another 30 days.
"The Ormsby case, up to now, is still in the documenting stage between prosecutors and the police, back and forth," the lawyer said on Monday.
"The way I see it, this case is weak and I've told this to the police, but the police are convinced they should go on."
He says Ormsby could be detained without charge until June.
Ormsby has told police there was a party at the Canggu villa, but by the day of the drug bust, the acquaintances she partied with had gone home.
Sydney musician Azaria Byrne came forward as the man who had rented the villa before handing the keys to friends and going home.
Another Australian, identified in media reports as Sydney DJ and Ormsby's former lover Marco Mazzucco, was also linked.
Witnesses say he was questioned by Bali police but allowed to return to Australia.
Ormsby is the only person arrested in connection to the case, after her arrest at the scene by drugs squad investigators.
