It should not just be office holders on the spot over entitlement misuse. If political parties benefit from the presence of an elected politician, they should be in the frame as well, writes Terry Barnes.

In the furore about Speaker Bronwyn Bishop's use of a luxury helicopter to take her from Melbourne to Geelong late last year, the focus has been on her judgment.

The fact that she used her travel entitlements as a parliamentary office-holder to attend a Liberal Party fundraiser, rather than strictly parliamentary business, is just as important.

Certainly, the Labor Opposition thinks so. While Bishop has admitted no wrongdoing, the Manager of Opposition Business, Tony Burke, is calling for the Speaker to release forms showing whether she authorised the charter for official business. While some might say that attending party events is part of a senior MP's expected public duties, Burke says that if she knowingly signed off on the charter for a Liberal fundraiser, "She can't stay as Speaker, absolutely no way."

Whether or not Burke is right, if Bishop thought that her party commitment could be passed off given her nominally impartial office, she is out of touch. Even Treasurer Joe Hockey and Social Services Minister Scott Morrison thought Bishop failed to pass the "pub test" about what is acceptable and what isn't.

While the political judgment of someone who, back in the 1990s, briefly was the Coalition's leadership hope was not so much faulty as non-existent, Bishop was almost certainly within her rights as a public office holder to use her travel entitlements as she thought fit. She accepted an invitation to a function and now she must account for how she honoured that undertaking.

That the Speaker is not the first MP using taxpayers' money for party and private events is no excuse. That both sides of politics have long turned blind eyes to the problem is no excuse either. Labor's unctuousness in pursuing Bishop is predictable but hypocritical. Cocking a snook at voters over MPs' entitlements is, sadly, bipartisan.

Indeed, on social media yesterday Coalition supporters defending Bishop had no trouble citing tit-for-tat instances of Labor ministers, including former prime minister Julia Gillard, using taxpayer-funded aircraft to attend private events - although in most cases politicians of both sides window-dress such episodes with some official business giving the trip some legitimacy, as Gillard did when attending the Byron Bay wedding of senior Labor staffers shortly before she lost to Kevin Rudd in 2013. Similarly, the current PM and other Liberal MPs have been called out for using official entitlements to attend a colleague's wedding.

Bishop's helicopter vision reflects very poorly on all sides of politics. The rules were stretched but are so rubbery that they probably were not broken, and if they can be flown through they need fixing. But it should not just be the Speaker, ministers and office-holders on the spot. If political parties benefit from the presence of an elected politician, they should be in the frame as well.

It was right for the Speaker to write a cheque to reimburse the costs of her helicopter charter. But her party shares responsibility for her actions, yet gets off scot-free. There would have been no trip and no charter had the Liberal fundraiser's organisers not invited her.

In business, boards and chief executives are ultimately liable for the actions of judgments of their subordinates. Why can't the same principle be applied to political parties when it comes for accountability for public moneys spent on their behalf?

If a party fundraising event, like the one using Bronwyn Bishop as its drawcard, involves an extraordinary use of public money, not only the MP should be required to cough up in respect of personal entitlements such as travel allowances. National presidents and secretaries of the party that brought them there should also pay a penalty equivalent to the wrongly-incurred cost.

It wouldn't matter if the event was organised by a local branch or party-affiliated fundraising group. If the party is the ultimate beneficiary of the expenditure, then the buck should stop at the top.

This isn't to say that top party officials do encourage or condone ill-judged decisions by their parliamentary representatives - far from it. But if those same party figures have personal skin in the game, they would have powerful additional incentives to ensure MPs do the right thing by taxpayers as well as their party.

And if that liability extended to parliamentary party leaders - the Prime Minister, Leader of the Opposition and Leader of the Greens - they might also strive still harder to ensure their troops pass the pub test.

There is nothing essentially wrong with senior MPs like the Speaker as well as government and opposition frontbenchers attending party events using scheduled commercial flights and booked cars, provided they are already on justifiable official business. This is especially so when they're engaging with members of the public as well as party faithful.

But while the actual travel rules are too lax and must be tightened (as former Democrats leader Andrew Bartlett suggests elsewhere in The Drum), when a political party is the principal beneficiary of a senior MP’s travel entitlements, party officials should be directly accountable when the money of those whose votes they seek is misused on their behalf.

Terry Barnes is a policy consultant who formerly advised Howard government ministers. Twitter: @TerryBarnes5.