A $31 million "compromise" upgrade of Adelaide's chronically overcrowded courts precinct will deliver nine new courtrooms and a shiny entrance lobby on Gouger Street.

Key points: Three brand new courtrooms and upgrades to six others

Three brand new courtrooms and upgrades to six others Chief Justice says the project will help clear case backlogs

Chief Justice says the project will help clear case backlogs Construction expected to start late this year and finish in 2020

The works will take in the historic Supreme Court building, on the corner of Gouger and King William streets, and the Sir Samuel Way building which fronts onto Victoria Square.

Chief Justice Chris Kourakis told the ABC the plan comes after the abandonment of a massive new court building under the Weatherill government.

"A $400 million proposal for a court complex to house Supreme Court and District Court courtrooms wasn't funded some years ago," he said.

"This is a compromise which will give us at least the functionality if not the standard of work that was to be offered before."

How the $31m upgrade will look from Gouger Street. ( Supplied )

The upgrade will create three new criminal jury courtrooms on the top level of the Sir Samuel Way building, and fix up six old and "dilapidated" courtrooms in the Supreme Court building.

"There is a backlog in crime in particular because of a lack of courtrooms," the Chief Justice said.

"The purpose is to ensure we have enough courtrooms to deal with our lists."

An artist's impression of a new-look courtroom. ( Supplied )

The president of the SA Law Society, Tim Mellor, said the upgrade was sorely needed and the courts should not be a poor cousin to other public facilities.

"Parts of the building are very old and inadequate in terms of basic things like toilet facilities," he said.

"This [upgrade] is a reasonable expectation for the community, on the same sort of level as things like proper facilities for health and education."

The current Supreme Court building on Victoria Square. ( ABC News: Eugene Boisvert )

Mr Mellor also hoped the Supreme Court building upgrade would also address poor disability access in its two oldest courtrooms.

The Law Society also wants the Courts Administration Authority to ensure regional courthouses are well maintained and utilised.

The scope of the project is currently before the State Commission Assessment Panel.

It is expected construction will start late this year and finish in 2020.