TORONTO - Two top political aides to former Ontario premier Dalton McGuinty pleaded not guilty Monday to charges over the destruction of internal emails about the Liberal government's costly cancellation of two gas plants.

Foreshadowing what is expected to be a bitterly fought case, the long-awaited trial of David Livingston and his deputy Laura Miller finally began with an attack on the prosecution over the information it had provided the defence, leading to a week-long delay in hearing evidence.

Livingston's lawyer, Brian Gover, stopped short of alleging Crown misconduct but slammed the quality and timeliness of the disclosed materials.

“The police notes are cryptic, unusually sketchy, as if by instruction,” Gover told Ontario court Judge Timothy Lipson. “The defence has no idea what facts the witnesses really conveyed.”

In asking for a delay in what was expected to be a six-week trial, Gover said the prosecution had now cut its proposed witness list in half to 12 without explanation.

He complained the prosecution was refusing to provide notes on recent interviews - some lasting several hours - with witnesses, who in several cases appeared to have provided new information and documents not shared with the defence.

“We should know what was discussed during these interviews,” Gover said. “Defendants have a constitutional right to know the case they have to meet; they simply want to know what facts the witnesses shared.”

Police allege Livingston, McGuinty's chief of staff, and Miller hired her partner, a computer expert under contract to the Liberals, to wipe clean about 20 hard drives in the premier's office in 2013.

The drives apparently contained emails about the Liberals' decision to cancel the gas plants just before the 2011 provincial election. The decision set off a political firestorm given the estimated $1.1 billion the cancellation cost taxpayers and led to McGuinty's later resigning under a cloud.

The ensuing police investigation, Gover said, stemmed from a politically motivated complaint by the opposition Conservatives.

“They were seeking to maximize the gas-plants scandal,” Gover said.

Investigators charged Livingston and Miller in December 2015 with breach of trust, mischief and unlawful use of a computer.

Prosecutor Tom Lemon said he had no problem with an adjournment, even as he suggested the defence was over-reaching with its disclosure complaints.

The prosecution, he said, was prepared to provide a table to the defence that outlined what each new or different information witnesses had provided compared to what they had previously given.

He also undertook a “second look” at police notes to see what further information could be handed over. However, he balked at providing notes of discussions between the prosecution and its witnesses, saying those were privileged.

The defence pressed for the judge to vet the prosecution notes to make sure they should be kept secret, and asked that reasons for dropping witnesses be disclosed.

Lemon, however, explained some witnesses had simply turned out to be redundant or to have no useful information.

“What it sounds like to me is the normal assessment the Crown makes of his or her case,” Lipson said.

Gover later called the Crown's explanation “acceptable,” but said he reserved the right to raise the dropped-witness issue in future.

Lipson did warn the prosecution that any new interviews with witnesses in the coming days or weeks should be done carefully, with thorough note-taking.

“Cursory or cryptic notes should be avoided,” he said.

While evidence is now slated to start Sept. 18, Lipson did ask the parties to return to court on Thursday so he could assure himself the trial will get started in earnest.

“It's a very unfortunate turn of events that we couldn't start the evidence today,” Lipson said. “I want to monitor the situation.”