UPDATE: 4/3/2012, 6.57 p.m. The seventh paragraph has been updated to reflect the Kwok brothers’ public response to their arrest.

In Hong Kong, big property developers sit at the very top of the food chain. So the arrest last Thursday of two of the biggest–billionaire brothers Raymond and Thomas Kwok, co-chairmen of Sun Hung Kai Properties Ltd.–on suspicion of bribery has unleashed a media firestorm in the Asian financial capital.

It has also put a global spotlight on the hard-charging Hong Kong law enforcement agency that arrested the two tycoons: the Independent Commission Against Corruption (ICAC).

“The ICAC are a very serious organization,” says one veteran Hong Kong litigator who asked to remain unnamed because he may become involved in the case. “Anybody who doesn’t take them seriously is an idiot. They’re highly motivated, uncompromising, energetic, and incredibly thorough. You don’t want to get anywhere near their neck of the woods.”

Formed under British rule in 1974 to tackle endemic corruption across Hong Kong’s public sector, the ICAC spent the 70s and 80s aggressively rooting out the tradition of paying “tea money” to public servants. Among Hong Kong residents, the commission is most famous for tackling widespread corruption in the police force, a campaign dramatized in a 2009 action film, called I Corrupt All Cops. Today, Hong Kong is routinely rated as one of the least corrupt places to do business in Asia. (Transparency International’s Corruption Perceptions Index ranks it 12th-cleanest of 182 countries.) And the ICAC, which has increasingly focused on private-sector corruption in recent years, gets much of the credit for that.

“The ICAC has a very clean image among the Hong Kong people,” says defense lawyer Stephen Hung, who compares their reputation to that of the Prohibition-era Untouchables, at least the Hollywood version.

In going after the Kwoks, the ICAC has set its sights far higher than dirty cops, though. The company that the brothers control, Sun Hung Kai, is the largest property developer in Asia and owns Hong Kong’s two tallest buildings, the International Finance Centre and the International Commerce Centre. Forbes estimates their combined wealth at $18.3 billion, making the Kwoks the 27th-richest people in the world.

Along with the Kwoks, the ICAC also arrested Rafael Hui, Hong Kong’s former number-two official as chief secretary and head of the civil service. Earlier this month, the agency also arrested Thomas Chan, an executive director at Sun Hung Kai. All have been released on bail. In a press conference Tuesday, the Kwoks told media that they had not done anything wrong.

No charges have yet been brought against the Kwoks, and the ICAC has not released any information on its ongoing investigation. (In Hong Kong, as in the United Kingdom, it is possible to arrest suspects without charge.) Hung says the ICAC could conceivably take up to another year to investigate the case, though he notes that such a high-profile case almost certainly began a long time ago.

The parties will certainly be able to afford a robust defense. According to a source familiar with the case, Thomas Kwok has retained lawyer Lawrence Lok while Raymond Kwok has hired Gary Plowman. Both hold the title of senior counsel, an honorific given to veteran litigators in Hong Kong.

Mayer Brown JSM previously represented Raymond and Thomas Kwok in their dispute with their older brother Walter, who sued to block a vote removing him as chairman in 2008, but the firm declined to comment on any current representation. Likewise, Clifford Chance represented Sun Hung Kai and several board members in that dispute but also declined to comment on the present case.

If charges are brought, the government’s case would be handled by Hong Kong’s Department of Justice. The department has already issued a statement saying that any case would be handled by Kevin Zervos, the director of public prosecutions and an official who has no previous connection with Hui.

The ICAC is likely to remain highly involved in the matter though. Hung says ICAC officers who come to court frequently confer with prosecutors and actively seek to help address questions raised by defense lawyers. “You will never see the regular police do that,” he says.

ICAC’s strong public image, as well as higher salaries, helps the commission attract better-qualified investigators than, say, the police. A number of ICAC investigators are lawyers, some of whom eventually switch to the defense side. But most are fully committed. “It appeals to a certain evangelical mindset,” says the veteran litigator.

But Hung says the zeal of the ICAC has its downsides. The commission’s aggressive tactics have often been criticized, especially its use of wiretaps. Hong Kong law has long been more friendly to electronic surveillance than, say, that of the U.S. Some kinds of wiretaps do not require judicial permission. Moreover, unlawfully obtained evidence is not automatically excluded; a court can decide its probative value outweighs any prejudicial taint.

Indeed, it’s a common belief among defense lawyers, says Hung, that the ICAC regularly listens in on their phones. “It could just be lawyers’ paranoia,” he says, “but there have been times when it seems the prosecution is a little too prepared.”

The ICAC actually targeted two prominent defense lawyers in one high-profile case. Kevin Egan and Andrew Lam, who had successfully defended a number of ICAC cases, were both convicted in 2006 on charges they had attempted to interfere with a witness in an ICAC corporate fraud probe. Egan and Lam, neither of whom returned calls seeking comment, were both exonerated on appeal in 2010.

Email: alin@alm.com