Anne Duffy and the lawyer, Stephen Raymond Stubbs, met in November 2008, when Ms Duffy's son Alexander Duffy was arrested and charged with assault and an act endangering life.

Duffy had applied for and was granted funding from Legal Aid ACT – a means- and merits-tested service that funds legal representation for people who can't afford to pay.

Duffy nominated Stubbs, 63, as his preferred lawyer.

His charges were later upgraded and replaced with conspiracy to commit murder. He was also later charged with further assaults while out on bail in February 2009.

It's alleged by the Crown that Stubbs received about $4000 from Legal Aid for legal services in relation to Duffy, then 19, while also being paid more than $30,000 from Ms Duffy.

Ms Duffy told the ACT Supreme Court at Stubbs' trial on Tuesday she was approached by the lawyer at court "early in the piece".

She said Stubbs had explained to her there would be legal costs following her son's arrest and charges.

"[He said] he was doing the best by me ... and he would do me a favour by only billing me what Legal Aid would've paid him."

She said she understood her son had not received a Legal Aid grant, and over the next months Stubbs would phone and email her for money to fund his appearances in court.

Ms Duffy said early on Stubbs had asked her to bring $5000 in cash to the ACT Magistrates Court one day before Duffy was due to appear. She described visiting a cafe before her son's appearance that day, and running into Stubbs.

She told the court Stubbs paid for her coffee, and when she offered him a manilla folder with the cash, he refused to take it while inside the coffee shop.

She said she later gave it to him outside.

Ms Duffy told the court she had borrowed money, sold antiques, and been secreting cash away to make up the $5000.

She said Stubbs had asked for cash payments, but that she was too busy at work to always withdraw money, and so they arranged electronic transfers instead.

She told the court how she had arranged to draw on her mortgage to make the payments Stubbs was requesting.

She said she was "going to do anything and everything" she could to fund her son's legal representation in court.

"I just put all my trust in Mr Stubbs to do everything for my son," she said under questioning from prosecutor Katrina McKenzie.

Ms Duffy said she emailed Legal Aid in 2009 in an attempt to find out about funding for her son's matter, but said she received a reply that they couldn't talk to her without Duffy's permission.

But she told the court she couldn't talk to her son about his legal troubles, as he had become distressed and closed off.

"I said I couldn't talk to my son about anything, as he wasn't talking to me," she said.

Stubbs' barrister Theresa Warwick did not have the opportunity on Tuesday before court adjourned to cross-examine Ms Duffy.

Stubbs faces 15 charges of dishonestly obtaining property by deception in relation to the allegations.

The trial continues before Justice John Burns.