It's the government department tasked with protecting Australia's democracy, yet within it bubbles accusations of a toxic culture, the silencing of dissent and the routine cover-up of problems.

The department governs Parliament House but some of its staff are so suspicious and fearful of those running it, they regard it as a workplace where "the walls have eyes".

The ABC has spent months speaking to public servants ? past and present ? plus politicians and their staff from both sides of the political aisle, as well as people who have worked across a range of professions at Parliament House, all of whom would only speak under the condition of anonymity.

Repeatedly and without prompting the word "toxic" was offered about the Department of Parliamentary Services (DPS).

And yet efforts to scrutinise its operations, its management and practices are practically impossible ? by design.

That's because DPS has been granted extraordinary and unique isolation from standard methods of scrutiny ? and by someone who once promised to meet the public's higher expectations.

The department is exempt from Freedom of Information laws ? a change Anthony Albanese, as the then leader of the House of Representatives, introduced as an "interim measure" more than a decade ago.

To its critics, DPS has largely been overlooked in the reckoning that happened at Parliament House in recent years, where a spotlight has been shone on the culture and treatment of staff following Brittany Higgins's allegation of rape in a ministerial office.

Inside the department, there's a sense of despair that little has changed in the three years since a landmark report described DPS "as being particularly driven by fear" and said there was a culture of silence in the parliamentary departments that had a "chilling effect on reporting misconduct".

But few ? if any ? in the government are showing an appetite to bring about changes at a department that receives hundreds of millions of dollars in taxpayer funds annually.

It comes amid reports that the boss of the department, secretary Rob Stefanic, had a relationship with his deputy secretary, Cate Saunders .

Neither Mr Stefanic nor the parliament's powerful leaders ? Speaker of the House of Representatives Milton Dick and President of the Senate Sue Lines ? are willing to offer any information about how they managed a relationship between the department's two top public servants, who collectively earned close to $1 million.

The ABC put 14 questions to DPS about its culture, the disclosure of Mr Stefanic and Ms Saunders's relationship and the department's approach to information requests. The bulk went unanswered.

"The Secretary maintained a professional working relationship with Ms Saunders for a number of years before her employment by Services Australia in April 2023," a DPS spokesperson told the ABC.

"The Secretary declares all relevant relationships in the appropriate manner."

However, Mr Stefanic offered further comments following a chance encounter the day after DPS supplied its written statement. Unprompted, the secretary said he hoped "nice things" were being written about him before dismissing the allegations as "gossip and rumour" ? words not included in the statement his department issued.

The ABC put a further 18 questions to Mr Dick and Senator Lines, and received a two-sentence response.

Even information requests to gain insight into the maintenance of Parliament House's iconic flag pole have been repeatedly rejected by the department. In March last year, facing furore about flying a tattered flag about Parliament House, the presiding officers confirmed the lift to the top of the pole was "urgently undergoing maintenance" yet the ABC has been denied any requests to gain further information about the maintenance program.

The situation highlights the opaque nature in which the Department of Parliamentary Services is allowed to operate, where the only documents released are done so at the department's discretion.

Even the High Court and Office of the Governor-General are subject to FOI on administrative documents. Staff say without greater public scrutiny, deep-seated and long-lasting problems within the department are able to fester.

What is the Department of Parliamentary Services?

DPS is one of four parliamentary departments and is tasked with overseeing the functioning of a workplace for thousands of people. It reports to the parliament's presiding officers ? Mr Dick and Senator Lines, who are both Labor politicians.

The Human Rights Commission's Setting the Standard report , which the then Coalition government ordered in the wake of Liberal staffer Brittany Higgins' allegations, included interviews with staff who told the inquiry they "feared senior leaders within DPS".

"Participants told the Commission that the result of this fear was a culture of 'cover-up' and silence. Participants reflected on the consequences of not going along with this and described ostracism and targeted bullying," the report stated.

Staff the ABC has spoken with talked about a paranoia that exists within public servants. Some have received reprimands from their bosses for raising their concerns with politicians, others have been reprimanded for being seen talking in the corridor with members of the media.

Others have received veiled threats from senior figures when problems have been raised, while others say the department's monitoring of workers inside Parliament House extends beyond the public servants.

Two people the ABC spoke with say they've noticed some changes since Mr Dick became speaker, suggesting he is imposing greater accountability, but more broadly the department is accused of cultural problems that stretch back years ? a claim DPS rejects.

"The department offers various mechanisms for employees to report alleged misconduct," DPS told the ABC in a statement.

While not wanting to comment on specific allegations, a government spokesperson insisted "everyone has the right to a safe and respectful workplace".

Earlier this year while questioning Mr Stefanic, Shadow Finance Minister Jane Hume noted that given DPS was exempt from FOI, it left Senate estimates as the only forum in which his department faced scrutiny ? a claim he rejected.

That FOI exemption dates back to 2013, when Anthony Albanese introduced new laws, pending a broader review into Freedom of Information laws. That review recommended DPS administrative documents be subject to FOI. It recommended only the Parliamentary Library, which politicians use to obtain confidential research remain exempt from FOI. But neither Labor nor Coalition governments have adopted the recommendation in the years since.

ABC News contacted the now prime minister's office, in light of recent revelations about DPS, to see if Mr Albanese was satisfied his "interim measure" was still in place.

"Freedom of Information laws are essential to Australia's democracy," a government spokesperson said. The spokesperson later suggested "the government will continue to consider further FOI reforms" but offered no further details.

DPS senior leadership

Rob Stefanic became the secretary of the Department of Parliamentary Services in December 2015.

Annual reports show the department has undergone an almost doubling of its most senior staff in the last five years.

Cate Saunders joined DPS in December 2017 as the chief operating officer.

Mr Stefanic created the position of deputy secretary and appointed Ms Saunders to the role on an acting basis. In early 2020, she became permanent in the role, which reports directly to the secretary and has responsibility for Parliament House security.

"The Deputy Secretary role was advertised and a merit-based process was conducted, with three panel members, two of whom were independent of DPS," the department said in a statement.

Mr Stefanic and Ms Saunders regularly appeared alongside each other at parliamentary inquiries. In 2021, they attracted a rebuke from then opposition senator Katy Gallagher, now the minister for finance, women and the public service, in the wake of Ms Higgins's allegations. Mr Stefanic and Ms Saunders told senators that despite making a 13-minute training video for identifying "serious incidents" mandatory for staff, neither had watched the video prior to its approval.

Ms Saunders went on a temporary secondment to Services Australia in April 2023, where she served in the role of "general manager, people". It is an SES Band 2 position, which has an average salary of $287,362 across the public service, well below the more than $420,000 Ms Saunders earned at DPS.

A DPS memo, seen by the ABC, said Ms Saunders had initially gone on a six-month secondment and was due back in mid-October but after "some leave" she "decided to retire from the Commonwealth public service".

The ABC has put multiple questions to the presiding officers, DPS, Ms Saunders and the prime minister's office about when the relationship began, when it was disclosed and how it was managed. None have been willing to answer those questions.

According to multiple people the ABC has spoken with, the relationship was widely known within DPS prior to it first becoming public earlier this month.

The Australian Public Services code of conduct requires secretaries to avoid conflicts of interest and to disclose, on an annual basis, details of their personal interests and those of their immediate family.

In 2018, then-prime minister Malcolm Turnbull updated a code of conduct to stop ministers from having sex with their staff, following revelations deputy prime minister Barnaby Joyce and a staff member were expecting a child. That change only applied to ministers and not to public servants at Parliament House.

In response to questions, Ms Saunders said she had been "subjected to invasions of my personal privacy based on misogynistic and malicious gossip in the so-called public interest".

"The Jenkins review reflects on the culture of the media and the misuse of power in parliamentary workplaces. The nature of your questions and your naming of me sadly continues the unjustified bullying and harassment of me by sections of the media."

DPS and the government have also refused to release any details about Ms Saunders' departure from the public service.

"The Secretary did not initiate, nor have any decision-making role in that cessation," a DPS spokesperson said.

In a joint statement, the presiding officers said they had sought advice from the Australian Public Service Commissioner "on the matters that have been raised".

"The Commissioner was satisfied that all processes were followed," Mr Dick and Senator Lines said.

Mr Stefanic faced questions at a Senate hearing earlier this year about Ms Saunders' employment but at no time did he disclose their relationship.

He is due to again face Senate estimates on Tuesday.