It is now embroiled in a High Court legal battle with Crown prosecutor Margaret Cunneen, SC, over whether it can investigate her over allegations she attempted to pervert the course of justice.

It's a serious business. But amid the political resignations and legal wranglings, there have been some glorious moments of high farce. Here are ten of the best.

1. The Clinton defence

Moses Obeid leaves ICAC.    Photo: Nic Walker

If the Obeid boys take the ICAC seriously, they mask it masterfully in the witness box.

Moses Obeid, the wheeler-dealer middle son of corrupt former Labor powerbroker Eddie Obeid, channelled former US President Bill Clinton's famous denial when he was asked about his family's involvement in a controversial water infrastructure company.

"I can put that to you in a Bill Clinton fashion: we did not have investor relations in that company," Obeid jnr told the ICAC of his family's alleged stake in Australian Water Holdings.

"Was Mr Clinton telling the truth?" counsel assisting the ICAC, Geoffrey Watson, SC, shot back, to applause from the public gallery.

2. Scape-dog

Marie Ficarra and her miniature schnauzer.     Photo: John Veage

Pop culture is littered with famous pooches, from crime-fighting canines Lassie and Scooby Doo to Peanuts' Snoopy. It was only fair, then, that the ICAC had its own four-legged friend worthy of a spin-off television series.

Upper house Liberal MP Marie Ficarra told the ICAC that her miniature pet schnauzer, Leisel, was gravely ill on the day she allegedly discussed an illegal $5000 donation to the Liberal Party with property developer Tony Merhi. Developers have been banned from making political donations in NSW since 2010.

"It's not easy to take blood from a miniature schnauzer," she huffed, causing lawyers in the hearing room to lose their customary composure.

"Please don't mention the dog again," Watson warned.

After Ficarra's show-stopping afternoon in the witness box, "like getting blood from a schnauzer" became the standard quip for any ICAC witness who yielded their secrets reluctantly.

3. A land of droughts and flooded garages

Tim Koelma.      Photo: James Brickwood

Among the more interesting excuses for lost documents was a flood in the garage of Tim Koelma, a former staffer to one-time Liberal energy minister Chris Hartcher.

Watson labelled it the "great flood of 2011", while his sidekick, junior counsel Greg O'Mahoney, mused that it must have been an "aggressive leak" to damage a wide variety of household objects.

"I think that it claimed a bike?" O'Mahoney deadpanned.

"Yes, it claimed a lot of different things," Koelma's wife rejoined.

4. Blame it on the hard drive

Darren Webber.    Photo: Nick Moir

Technology is a temperamental beast. At least two ICAC witnesses found themselves in the awkward position of having documents that would help prove their claims located on hard drives that were damaged beyond repair.

First-term Central Coast Liberal MPs Chris Spence and Darren Webber, both of whom were asked to explain allegedly illicit donations from property developers, said technology dramas were thwarting their efforts to show the cash was for legitimate work.

"I took it to a computer place to try and get it fixed and it was irreparable," Spence said.

Days later, Webber said his computer had been struck down with the very same affliction.

"Again we're left in the unfortunate position where there isn't one record on paper or in electronic form which can verify what you're saying, is that right Mr Webber?" Watson asked.

"In the face of the current accusations, it's incredibly unfortunate, yes," Webber replied.

5. Not so smart

Arthur Sinodinos.   Photo: Cole Bennetts

As ICAC Commissioner Megan Latham warned the hordes of Sydney barristers appearing at the commission, the microphones on the bar tables were sensitive enough to pick up asides that were not intended for her (or our) ears.

Liberal Senator Arthur Sinodinos' highly respected silk, Tony Bannon, was caught off guard during his questioning of financial whizz kid Rod De Aboitiz, who was none too impressed with Sinodinos' performance as the former chairman of Australian Water.

"Smart arse," Bannon muttered as De Aboitiz referred to Sinodinos repeatedly as the former Assistant Treasurer.

Bannon was forced to apologise for the "disgraceful" comment - which is probably among the least offensive remarks caught by the keen-eared transcription staff at the ICAC.

6. Tinkler gets terse

Nathan Tinkler.    Photo: Rob Homer

Embattled coal mogul Nathan Tinkler, ever the shrinking violent, was similarly frank in his assessment of the ICAC.

"This is some of the most boring shit I've ever seen," the brash 38-year-old was heard to say as the inquiry into political donations took a brief adjournment.

In one email shown at the commission, Tinkler described the former state Labor government as a "bunch of deadbeats" and their Liberal successors as "a bunch of pricks scared to make a decision" about his plans for a coal loader in Newcastle.

He's being investigated over donations his property development company gave to the Liberals before the last election. 

7. No powder puff

"Jesus, Mary and Joseph!" former premier Kristina Keneally exclaimed from the witness box.

"The powder room! Are you serious?"

The silk acting for corrupt former ALP powerbroker Joe Tripodi had put it to the former premier that a key conversation about Australian Water had taken place in her office "powder room".

"I can assure you that nobody came into the powder room of the Premier's office at any point and I'm sorry to laugh but that is the most laughable proposition I've heard," Keneally said, to guffaws from the public gallery.

Tripodi's barrister later offered to supply "a diagram of the Premier's office if it's necessary for the commission" - an offer the Commissioner seemed reluctant to take up.

8. Wolfe of Macquarie Street

Michael Costa.      Photo: Edwina Pickles

"I feel like, what's that bloke in the Pulp Fiction movie ... Winston Wolfe, you know," former NSW Labor treasurer Michael Costa told the ICAC.

Costa, a one-time chairman of Australian Water, is one of a handful of politicians to escape the ICAC witness box unscathed.

He told the commission he felt like Mr Wolfe - a sharply dressed fixer and cleaning specialist - as he tried to fix up Australian Water's financial mess.

The commission has heard the company was billing the state-owned utility Sydney Water for a range of extravagant expenses, including limousines, airfares and political donations.

If that wasn't bad enough, Costa said that he had heard that pole dancing was among the company's "staggering" expenses.

9. Better than a shoe phone

Lee-Jay Brinkmeyer.     Photo: Daniel Munoz

Sometimes it's the lesser-known witnesses who yield the most extraordinary evidence. Property developer Lee-Jay Brinkmeyer, who fronted the ICAC to give evidence about his $20,000 donation to an alleged Liberal Party front organisation, got into a pickle when he was asked when he last spoke to a party official.

Asked to hand over his phone, Brinkmeyer produced a "travel mobile phone" - which, rather curiously, forensic experts found had "absolutely nothing" on it.

He admitted he hadn't been anywhere much but the ICAC for the past two years.

"So this is in ICAC travelling phone, is it?" junior counsel Greg O'Mahoney deadpanned.

Brinkmeyer couldn't recall whether anyone might have told him to pack a "clean" mobile phone for the trip to the ICAC, but he did tell the commission that he bought it on eBay and it had a "wonderful little dock".

"This is just getting ridiculous," O'Mahoney said at one point.

"Yeah, that's true," Watson piped up.

10. Icing on the cake

Jeff McCloy.     Photo: Cole Bennetts

For some, it was the photo that took the cake. Colourful property developer and one-time mayor Jeff McCloy posed with a birthday cake shaped like a brown paper bag overflowing with cash after fronting an inquiry into illegal political donations.

McCloy resigned as Newcastle mayor in August after admitting to giving envelopes stuffed with $10,000 in cash to two former Liberal MPs before the last state election, in breach of NSW laws banning donations from developers.

"I feel like a walking ATM some days," he told the ICAC. "They all come to see me for money."

"It's a dangerous reputation to have," Commissioner Megan Latham rejoined.

McCloy apologised for the cake gaffe and put it down to the "bad judgment" of one of his guests.