His appearance will add further weight to a controversial push to decriminalise the use of cannabis for the treatment of sick and terminally ill patients.

Lucy Haslam, whose 24-year-old son Daniel has been using cannabis for relief of nausea, vomiting and poor appetite related to chemotherapy for the treatment of bowel cancer, has organised the symposium with the support of state government funding.

To be held in Tamworth on Friday and Saturday, the symposium follows Mr Baird's public support for finding a way to use cannabis as a medical treatment for illnesses such as cancer. The symposium will host a range of Australian and overseas health and legal experts to discuss the merits of the treatment.

Earlier this year, Nationals MP for Tamworth Kevin Anderson drafted a private members bill to allow terminally ill patients to use cannabis.

Mr Baird later announced the NSW government would run clinical trials of the drug. The trial will be devised by a working party that will report back to the government by the end of the year.

Prime Minister Tony Abbott has thrown his support behind the planned trial.

Mr Baird has also said the existing police discretion to not charge terminally ill adults if they are caught using cannabis for pain relief would be formalised through new guidelines.

He said the clinical trial would "explore further the role cannabis can play in providing relief for patients suffering from a range of debilitating or terminal illnesses".

Last year, a NSW Upper House Inquiry recommended the state government approve use of cannabis for those suffering from chronic pain and amend the Drug Misuse and Trafficking Act to add a defence to cover the authorised use.

Health Minister Jillian Skinner indicated she would not support the recommendation but wrote to the federal government asking for further clinical research on the issue.

Ms Haslam said Mrs Skinner and the Australian Medical Association had declined her invitation to the symposium.