JOHN CHRISTENSEN runs the Tax Justice Network, a group that campaigns against tax evasion and corruption. A decade ago, its message fell on deaf ears. No longer. After the Panama papers leak last month, Mr Christensen says international media were camped at his door for days, seeking his views on how to stop dodgy dealings.

Corruption has flown up policy agendas, thanks to the work such crusading groups have done to reveal the extent of hidden offshore wealth to angry voters facing austerity. On May 12th Britain will host an anti-corruption summit. Officials from around 30 countries, including America, Brazil and Nigeria, will attend.

Discussion will range from secret ownership of offshore firms to corruption in sport. It will, no doubt, end with a forceful declaration; commitments may be harder to extract. Campaigners are hoping for progress on corporate transparency, disclosure of payments in oil, gas and mining, and co-operation in cross-border corruption cases.

Cracking open shell companies is the most important of these. There is a correlation between graft and these anonymous vehicles: take investigations into a suspected multi-billion-dollar theft from 1MDB, a Malaysian state fund, which are focused on shell companies in the Seychelles and Caribbean. Tracing illicit funds to a shell’s bank account is of little use if you cannot identify the individuals who control it. This worries business people as well as policymakers: a recent survey of corporate leaders in 62 countries by EY, an accounting firm, found strong support for more openness in ownership; legitimate firms want to know whom they are trading with.

International standards on “beneficial” owners (the real people, as opposed to other firms, behind firms) have been tightened, but remain quite loose. The information should be collected somewhere, whether in registries or by company-formation agents, and made available to “competent” authorities when requested.

Practice varies greatly. Some offshore centres, including Jersey, have had (non-public) registries for years, having set them up under pressure after scandals—though they rely heavily on regulated formation agents to collect, verify and update information. In America, by contrast, agents are not licensed, and ownership information is not collected, let alone verified.

Momentum is shifting towards central registries. A new European Union directive calls on members to set these up and to make the data available to police, tax authorities and others with a “legitimate interest” (such as investigative journalists). Britain has gone further: it launched a public registry last month. Other countries, including Australia and the Netherlands, plan to do the same.

In principle, openness seems a fair exchange for the privilege of limited liability. But there are problems in practice. Those registries already up and running tend to be purely archival: they do not verify incoming information because of the cost. This tempts money-launderers to lie.

Britain plans criminal penalties for false declarations. But unless declarations are checked—and resources are stretched already—ne’er-do-wells may take their chances. Formation agents have little incentive to push for accurate information: monitoring of the industry, which falls under HM Revenue & Customs, is scant.

Britain’s overseas territories argue against public registries, partly on privacy grounds but also because they consider their “gatekeeper” model to be more robust. This places a duty on law firms, trust companies and other registration agents to collect and certify beneficial owners’ identity documents. The offshore centres argue that leaning on regulated entities, close to the client, is more practical and effective than relying on registries, which are further removed from the action and do not face the threat of licence suspension.

In Jersey, ownership information and the source of funds must be verified at registration. The regulator also makes checks, including to ensure that formation agents update information when ownership changes. By comparison, vetting on the British mainland is “rubbish”, says a regulator who has worked in both systems.

There are problems with the gatekeeper model, to be sure. Ownership information can get lost along chains of intermediaries. Some (though very few, it seems) conspire with crooks. Enforcement is patchy: Jersey has jailed rogue formation agents, but the British Virgin Islands does no more than pull licences, and even then only rarely.

Nevertheless, research suggests that, for all the criticism, offshore financial centres have done more to comply with beneficial-ownership rules in recent years than their onshore peers. That may be surprising in the light of the Panama papers and other leaks—but much of what they contain is 15 or even 20 years old. The most comprehensive study, “Global Shell Games” by Michael Findley, Daniel Nielson and Jason Sharman, was conducted in 2012. The authors e-mailed 3,773 formation agents around the world, posing as consultants looking to set up untraceable firms. Agents in offshore centres, they found, were much less willing to deal with them than service providers in OECD countries. Not a single one in Jersey or the Cayman Islands took the bait; dozens did in America.

The authors concluded that blacklisting had forced offshore centres to get tougher, whereas OECD countries had never faced equivalent pressure and could get away with being laxer. That could change with public registries—if more big countries follow Britain’s lead, and if both policing and punishment are strong. But Mr Sharman is not reassured by the blueprints on the table. Self-declaration without verification is, he reckons, the public-registry model’s weak point. As currently designed, it risks being “completely ineffectual”.