The image of a neatly dressed lobbyist striding through the halls of Parliament House is a familiar one in Canberra. But a fresh examination of the practice has put a spotlight on just how many advocates for corporate interests enjoy unfettered access to the nation's lawmakers.

The report, by the ABC's investigations team, documents lobbyists moving without restriction through the building's public and semi-public areas, often meeting with ministers, advisers, and backbenchers away from the official diaries. "They are professional persuaders whose job is to influence politicians," one MP told the ABC, speaking on condition of anonymity. "And they can be powerful enemies if you cross them."

Lobbying is a legal and regulated industry in Australia. The federal register of lobbyists, managed by the Attorney-General's Department, lists thousands of individuals and firms. However, the report notes that not all lobbyists are required to register – in-house corporate advocates and those working for non-profits are often exempt. This means the true number of people working to sway policy is likely far higher than official figures suggest.

Proponents of lobbying point out that it provides lawmakers with valuable expertise and industry perspective. "Our role is to ensure that when Parliament debates legislation, it has the full picture of the real-world impact on businesses and jobs," said a representative for the Australian Lobbying Association. "Without us, decisions would be made in an information vacuum."

Yet critics contend that the current system grants disproportionate access to deep-pocketed interests. "The revolving door between government and corporate advisory firms is legendary," said Dr. Sophie Tran, a political analyst at the Australia Institute. "When lobbyists can walk the corridors day after day, they build relationships that ordinary citizens can never match. That's a fundamental democratic imbalance."

The ABC report comes amid growing calls for tighter regulation. The federal opposition has flagged a review of the lobbying code, and several crossbench MPs are pushing for an independent integrity commission with enforcement powers. Meanwhile, the government maintains that existing rules are adequate, pointing to the mandatory lobbyist register and a ban on lobbying by former ministers for 18 months after they leave office.

But as the report makes clear, the physical presence of hundreds of lobbyists within the building means their influence may be more pervasive than any register can capture.