Wired on Friday: Unless the law muzzles them, search engines should act to document and make public what they do, both in the West and China.

MSN filters and takes down Chinese blogs that use keywords like "Falun Gong" or "democracy". Google has recently announced a self-censored version of its search engine for the Chinese market, with links to forbidden websites removed.

Yahoo!, when requested, handed over the details of journalist Shi Tao to the authorities, allowing them to arrest and sentence him to 10 years in prison for contacting the New York Website Democracy Forum via his Yahoo! e-mail account.

It's the price of doing business with China - but who, exactly, pays?

Tech companies such as these emerged and thrived in the open networks of the West. Now they seem as determined to assist in the censoring and surveillance regimes of the younger Chinese internet.

Do they have any choice? It's true that if they were not present in China, other domestic or state companies would be doing the same as them - or worse. And they are, as each of these companies repeatedly pronounce, merely obeying local law.

But there are ways a company can grudgingly comply with a law, and there are ways to generously acquiesce.

The United States department of justice, attempting to shore up its arguments for an anti-pornography statute that had been suspended on constitutional grounds, recently required that US search engines provide it with an exhaustive list of recent search requests.

Of the search engines sent a subpoena, only Google challenged the request, and is currently locked in a court battle to protect the privacy of its users (and, according to its complaint, defend the trade secrets of its database).

Is there much comparison between what the department of justice wants, and what China demands?

Although the situation is very different, one aspect sticks out. The companies involved would rather not discuss their dealings with the government.

Whether or not the companies should comply is one matter, but the fact is that all but Google choose to keep the matter confidential. If it hadn't been for the government having to publicly file a motion against Google, no-one would have known.

Even - perhaps even especially - when their own customers' rights are at stake, internet companies have been very evasive about how they comply with the law, in China or elsewhere.

The secrecy has great effect in more oppressive countries. The disappearance of MSN's dissident blogs was reported by its readers. It took the detective work of concerned activists to uncover that it was Yahoo! who passed on the details of Shi Tao to the authorities.

These companies are, perhaps, obliged to obey oppressive laws in China.

And perhaps their American CEOs are as unhappy with this state of affairs as their public pronouncements claim (Jerry Yang, Yahoo!'s founder, said he "didn't like the outcome of what happens", and Google's blog said that its self-censorship was "difficult").

But the most pernicious part of a repressive government's use of these companies as its big brother and chief censor, lies in the secrecy of its operation.

Unless the law itself muzzles them - and there are cases of secret proceedings in both the West and China - companies should act to document and make public what they do.

Every website they host, only to take down, should be listed with an explanation. Every page removed from their search engine should appear as a public record elsewhere.

This may seem like a great leap: but there's precedent. Whenever Google is told to take a page out of its database in the US, the removed page is marked as such in the search results.

If the removal is over a copyright concern, a record of the legal take down request is passed to a third party researching the effects of American copyright law on free speech and published on a site called chillingeffects.org.

When Google arranged a censored version of its search engine to please the Chinese government earlier this week, the company included one part of that arrangement.

Rather than just "disappearing" the pages from its index, Chinese readers will see a small message stating that some pages had been removed "in compliance with local law". They - and we - will have at least some idea of what is going on.

It's not much, but it's a start. An equivalent to the "chilling effects" site - a third party, outside of China, that receives a comparable list of what is being hidden from the Chinese public, and how, would be a suitable next step.

Yahoo! and other companies could publish statistics on how many responses to government identification requests - in the United States, Ireland, China, France - they are obliged to comply with.

The whole world has a right to know what our governments are doing. And if the net companies are happy to comply with local laws, they should be happy to tell the world exactly how compliant they are.