The government will introduce a bill into the Legislative Assembly on Thursday, which would allow the courts to show leniency to criminals who "facilitate the course of justice".

That includes making disclosures or admissions, either before or during a trial, or by helping to indicate which particular elements of the alleged offence are at issue.

Attorney-General Simon Corbell hopes the changes would drive efficiency in the court system, which continues to be plagued by lengthy delays despite the successes of other government initiatives.

“We know that inefficient use of time and resources in the criminal justice system contributes to court delays,” Mr Corbell said.

“The Bill that I have introduced today recognises that defendants and their lawyers have an important role to play in addressing delays in the system," he said.

The government says similar measures are employed in NSW, and that the territory's courts can look to that jurisdiction for guidance on applying the new provisions

Continuing delays in the ACT Supreme Court were again reflected in the budget papers.

Ten per cent of criminal cases and 24 per cent of civil cases in the Supreme Court were pending for more than 24 months in 2012-13.

The government has ensured that any reduction in sentences would not be "unreasonably disproportionate" to the seriousness of the offence.

“This will ensure visibility and allow the community to satisfy themselves that sentences continue to reflect the seriousness of the offences," Mr Corbell said.

"It will also ensure defence counsel can advise their clients appropriately.”