This post was contributed by Dr Ben Worthy, a lecturer in Birkbeck’s Department of Politics.

Last week David Cameron admitted that Westminster has a ‘problem’ with lobbyists. Governments have long struggled with lobbying. The Coalition has had its own share of scandal around ‘inappropriate’ influence, from former military chiefs to access to the prime minister.

However, finding a solution is tricky. Like many political issues, the solution depends very much on what you believe the actual problem to be.

Now, MP Patrick Mercer and three peers face allegations of misconduct after a lobbying ‘sting’ by journalists. As of Sunday 9 June, the controversy is spreading to Select Committee chairman Tim Yeo , and questions are being asked about Conservative election strategist Lynton Crosby. This is not only a Conservative problem – two of the peers suspended from their party are Labour.

Like ‘expenses’, the word ‘lobbying’ is now synonymous with corruption. David Cameron made this link explicit

“…secret corporate lobbying, like the expenses scandal, goes to the heart of why people are so fed up with politics. It arouses people’s worst fears and suspicions about how our political system works, with money buying power, power fishing for money, and a cosy club at the top making decisions in their own interest.”

In 2012, a report by the Political and Constitutional Reform Select Committee pointed out that lobbying is not all bad. Indeed ‘it is a fundamental part of a vibrant democracy’ – lobbying  ended the slave trade and gave us all seat belts. It is also a vital information channel for politicians.

It is the ‘perception of undue influence’ that is corrosive. So, the solution is to regulate and open up the system: sunlight, as a famous man argued, is the best disinfectant. The Coalition government has dusted off suspended plans to introduce a register of lobbyists, requiring third parties lobbying on behalf of others to sign a public register.  But why, given the continued allegations, is it so difficult to do?

How you define lobbying shapes the solution. The government pointed out in 2011 that ‘the scope of the register will in large part be set by the final definition of lobbying’.

In his statement last week Cameron defined the ‘problem’ in a particular way: ‘I think we do have a problem in Parliament with the influence of third parties’ – meaning those lobbying on behalf of others. The Committee had previously said that

“…a statutory register which includes only third party lobbyists would do little to improve transparency…as these meetings constitute only a small part of the lobbying industry. The Government’s proposals only scratch the surface.”

The groups consulted last year also felt a ‘third party’ definition was too narrow. Many ‘could not identify the problem that the register was aiming to solve’.

To further complicate things, any definition is also highly political. Does lobbying include church groups? Charities? And does it include, crucially for Labour, Trade Unions, as Cameron thinks it should?

The Committee overall took a dim view of a third party register:

“We recommend that the Government scrap its proposals for a statutory register of third party lobbyists…the proposals…will do nothing to improve transparency and accountability about lobbying.”

So is there a better solution? For the Committee, a well-functioning regulation ‘would include all those who lobby professionally, in a paid role, and would require lobbyists to disclose the issues they are lobbying Government on’. This would help ‘improve transparency about lobbying, and reduce public concerns about undue influence’ (see more here).

The government should also do more to ensure basic information, such as records of meetings published online, are kept up to date. But even keeping track of when and where lobbying is taking place is difficult. Speaker Bercow has restricted access to passes to Parliament pending an investigation. The site ‘who’s lobbying’ seeks to map who is doing what and where. Yet while having a pass and formal meetings with a Minister can be connected to lobbying taking place, where do you draw the line? Does dinner with an old (ex-minister) friend, who happens to work for company X, count as lobbying?

The key question is whether transparency promotes good behaviour or pushes bad behaviour even further underground. Work by Cornelia Woll and David Coen show how lobbying adapts to new and different systems. For example, the US has some of the strongest transparency regulations around lobbying. Yet lobbying still exerts huge amounts of pressure on politicians – see here and here. The reason is obvious – a study calculated that in lobbying over one tax issue, companies gained $220 for every $1 spent on lobbying, a 22,000% return. With such returns and no agreement on how to define it, no solution or regulation will fully ‘solve’ the lobbying ‘problem’.