The ACT Bar Association claim the changes, under consideration in the ACT Legislative Assembly, will institutionalise unfairness in the system by shifting the burden of proof against a person forced to defend against an allegation.

But the ACT government argues the Courts Legislation Amendment Bill 2015 will strike a balance between the rights of the accused and the interests of justice.

The bill has been introduced to speed up the finalisation of cases and improve efficiency as significant court delays continue to dog the ACT courts.

But bar association president Shane Gill, in an opinion piece on the issue, said the desired "practical improvements" and "efficiencies" in drafting the bill would actually create injustice.

"However, it almost goes without saying, that making court processes more 'efficient' at the cost of making them less fair gains no true improvement and no real efficiency," Mr Gill said.

"What is now proposed slides the balance further against an accused person, including an innocent but accused person.

"[It will institute] processes that undermine fairness and the ability to reach a just outcome, albeit more quickly, [striking] at the heart of the nature of the justice system."

Mr Gill said the foreshadowed efficiency measures should be viewed as part of a "slow but inexorable undermining" of the ability of an innocent person to defend themselves.

The barrister argued that, for the past 15 years. a series of significant changes to the way criminal cases were heard had damaged the ability of a person to defend against an allegation.

"Generally at each change the government of the day has asserted the need to weigh the interests of the individual against the general community interest.

"Two difficulties flow from such an equation. Firstly, it is in the community's interest that individuals are treated fairly.

"Secondly, if at each stage the judgment is made against the interests of the individual, soon enough the scales exhibit a significant imbalance against the individual."

Mr Gill said the new bill proposed that the accused person assist the prosecution – the same people who are accusing them – to prove the offence.

Mr Gill said that effectively forced the accused person to help strengthen the prosecution case against them.

He argued that the situation would create an environment where flawed evidence could be adjusted to overcome potential criticisms.

But Attorney-General Simon Corbell said the proposed changes provided a fair balance between the rights of an accused and the interests of justice.

"[By] allowing the Crown to have a reasonable opportunity to consider and respond to matters raised by the defence, and the interests of the territory in having an effective trial process," Mr Corbell said.

He denied the amendments that required pre-trial disclosure of expert evidence by both parties would limit defendant rights and privileges as it would only apply to evidence to be relied on at trial.

Mr Corbell said the only change would be to the timing of the disclosure.

"The provisions put a framework around the timing of the disclosure and require that both the prosecutor and the accused person give notice and copies of relevant expert evidence to each other within a reasonable timeframe.

"There is no requirement for a defendant to produce something that the defendant wasn't intending to produce."

Mr Corbell said the changes could help the accused, by reducing the length of trials through the removal of potential for adjournments if unforeseen expert evidence was presented after the trial had commenced.

"In most cases, shorter trials mean fewer resources expended by the accused person, the prosecutor and the courts."