The ACT government last month gave the green light to a nation-first pill testing trial at Spilt Milk festival in November, allowing consortium STA-SAFE to offer the service free to festival goers.

Solicitor Paul Edmonds said while he supported pill testing from a public health perspective, he was concerned those facilitating it could be found guilty of a criminal offence.

He said pill testing could be seen as "aiding and abetting" pill use by encouraging drug use.

"There may not be a problem for those festival goers who are clearly going to take illicit drugs regardless of the pill testing, but presumably there will be some who might think 'Well, I'm not going to put this in my mouth until I've got this tested first'," he said.

"So it's not at all clear to me why that would not amount to aiding and abetting that person's consumption of an illicit drug."

Mr Edmonds said to protect facilitators from possible prosecution, either drug possession for personal use needed to be decriminalised or section 45 of the Criminal Code needed to be amended, adding an exception for those conducting pill testing.

"The idea behind it is a good one, the harm minimisation philosophy is obviously sound and to be supported, I just think there needs to be a lot of safeguards and checks put into it," he said.

"Obviously it would be a real shame if something went wrong and it became a big legal mess that could mean there is no pill testing anywhere else in Australia for another 10 or 20 years."

He said while it appeared ACT Policing had agreed not to prosecute anyone involved in the trial, it didn't make it legally sound.

"What happens if there's a change of personnel within the police force? A different officer who says 'I don't believe in harm minimisation, I believe in zero tolerance'," Mr Edmonds said.

He was also concerned about possible civil lawsuits if someone who had their pills tested had an adverse reaction.

He said he couldn't see how the private agency would not be liable, saying any disclaimer could be useless.

"If I was a lawyer advising the private agency I'd be saying not only do we want complete indemnity from civil claims, we'd also want some special protections against some criminal charges," Mr Edmonds said.

ACT Law Society president Sarah Avery said it was supportive of pill testing and was available to review any legislation drafted.

"If specific legislation is required, it should promote harm minimisation and protect medical professionals and others involved in pill testing from criminal and civil liability," she said.

"Some of our members hold fears that without specific legislation, those involved in pill testing could be at risk of criminal or civil liability."

An ACT Health spokesman said the consortium STA-SAFE had not proposed any change to the law on illicit drugs in the ACT.

He said the possession, supply and use of illicit drugs remained illegal in the ACT.

"However pill testing is a method of harm minimisation and aims to keep people safe," the spokesman said.