In August, magistrate David McLeod criticised the practice of the Independent Commissioner Against Corruption issuing search warrants for his own investigators, reportedly likening the practice as “Caesar going to Caesar”.

He ruled a series of warrants unlawful in the case brought against former Transport Department officer Michael William King, who is facing charges of unlawful possession and failing to act honestly.

The magistrate said the warrants “lacked specificity as to the nature of the offence or offences being investigated and the things that were sought to be seized”.

Three months later, McLeod ruled that evidence procured under those warrants were inadmissible at trial, telling the court that “the public must have full confidence in its institutions and in particular those institutions with coercive powers designed to oversee other institutions and individual conduct”.

“It is the actions of the Commissioner himself that bear the closest scrutiny,” he said in his decision.

“With warrants issued under the hand of the Commissioner, it is the Commissioner himself who must be appraised and satisfied about specific circumstances then determine if there are grounds to issue the warrant for a specific purpose before authorising one of his investigators to execute it.”

The decision was widely regarded as having potential flow-on effects on other ICAC investigations, with Lander himself telling a parliamentary inquiry last year “the consequence of that will be all warrants issued by me… are invalid… which will be an extraordinary result”.

But in a decision handed down last week, Supreme Court Justice Anne Bampton overturned the magistrate’s decision, after an appeal brought by the Director of Public Prosecutions.

Bampton granted the appeal, finding that “the Commissioner was authorised [under the state’s ICAC Act] to issue the ICAC warrants and each warrant was validly issued pursuant to the requirements of the Act “.

“I set aside the 28 August 2018 ruling that the ICAC warrants are invalid,” she found.

“I set aside the 16 November 2018 ruling excluding the admission of evidence obtained under the authority of the ICAC warrants.”

King’s lawyers had contended that the ICAC warrants were also invalid because they “did not identify the offence or offences the subject of investigation or identify the kind of items that might afford evidence of the unspecified class of proscribed conduct”.

However, Bampton found that the Act “did not require that the warrants state ‘the nature of the offences being investigated and the things that are to be seized’, nor for “a suspected offence to be recorded on the warrants”.

“Each of the ICAC warrants disclosed the jurisdiction of the Commissioner pursuant to the Act,” the judge found.

“In accordance with the requirement [under the Act], each warrant recorded that the Commissioner was ‘satisfied that the warrant [was] reasonably required in the circumstances for the purposes of an investigation into a potential issue of corruption in public administration’.”

The issue sparked a political and legal storm late last year, when Lander told parliament that he “did not agree” with McLeod’s decision, and arguing that court was “at the lowest level of the judicial process”.

“Shouldn’t we wait and see what the Supreme Court says?” he said at the December hearing.

Those remarks – and a separate interview on ABC radio in which Lander said he would be “astonished” if the DPP did not appeal the decision – prompted McLeod to take submissions on whether the entire proceedings should be stayed as a result of the Commissioner’s comments, which he said appeared to “challenge the court’s rulings”.

“This trial, the result of an ICAC investigation, is still of course underway [and] is accordingly sub judice,” he told the court in December.

However, later that month, McLeod declined to grant an application for a permanent stay of proceedings, but noted in his ruling: “It is unfortunate and indeed regrettable that [Lander’s] comments were made on each occasion in a way and in circumstances where it became possible to adversely interpret them.”

Lander did not comment on the matter today, with his office citing the fact the King matter was still before court.