RMB Lawyers' Ms Grimes will spend four months in New Orleans with Reprieve Australia, an organisation that provides legal representation and humanitarian assistance to people sentenced to death.

"As a lawyer, it is the most important case you can do because the outcome is someone's life," Ms Grimes said.

"I've always had an opposition to the death penalty and I've always been very passionate about the need for people to work these cases, which are very difficult.

"The clients are usually very poor, often have intellectual or mental disabilities and many are illiterate."

Ms Grimes said she was looking forward to the opportunity to expand her experience and work with some highly respected legal professionals.

"It's a way of being able to give something back and participate in the human rights process," she said."It's going to be a challenge.

"The entire (US) legal structure and court system is different, so I will be very much thrown in the deep end.

"I am nervous. The cases are going to be extremely difficult and there will be a culture shock because it's the first time I've been to the US.

"It's a largely African American population and poverty is rife, particularly in New Orleans, where I'll be based.

"It also has the highest crime rate of any state in the US and a high murder rate."

Ms Grimes will be working on original trials and appeals. Although she will be dealing with some terrible crimes, she said working closely with prisoners would help her to recognise their humanity.

"They have families, they have friends, they had a childhood," she said.

"When you interact with them on that basis, it's very difficult to see them as just their crime."