The recent case of jailed Rio Tinto executive Stern Hu sounded a warning to foreigners to be careful how they go about business in China. If anyone did not heed it, the eight-year sentence imposed on American geologist Xue Feng leaves no excuse. It flags an uncharted legal minefield of vague state security laws. The differences in the two cases reveal a worrying trend. Hu admitted bribery, although his conviction for stealing secrets about China's iron-ore trade was tainted by lack of transparency. Xue was convicted of the more serious charge of trying to obtain and traffic in state secrets, after allegedly negotiating the sale of an oil-industry database to a US energy consultancy. There has been much support since for his argument that he only collected data that national oil sectors around the world make public. US President Barack Obama has personally raised his case with President Hu Jintao and Washington is now demanding that he be granted immediate release on humanitarian grounds. There can be a fine line between collecting business intelligence and industrial espionage. It has been blurred on the mainland by recent draft regulations which say that if key state companies declare something a business secret, it qualifies as a state secret. The potential for freely available information to be labelled a state secret is obvious. Mainland authorities have long known of defects in state secrecy laws. The latest attempt at revision failed to tackle a lack of clarity and transparency that has led to widespread abuse. State secrets are defined as matters in the areas of politics, economy and national defence that involve national security and interests and could harm either if exposed. Even if subject to judicial interpretation in open hearings, that is broad enough to worry businesspeople, academics, students and journalists. But it is not defined by judges. It is the State Security Bureau that determines whether something is a state secret, making the process arbitrary and unpredictable. Once a charge of violating state secrets is laid, the authorities can limit lawyers' access to their clients and to details of charges and evidence. They can also order closed hearings, Hu's and Xue's being cases in point. Questions have been met with assertions that the mainland's 'judicial sovereignty' brooks no interference. China's increasing role over the years in the development of international law has raised hopes that foreigners' rights, at least, might be respected. But this has not been reflected in the nationalistic tone of prosecutions. For example, in 1995 the relevant ministries and the top courts ruled that in foreign-related cases, a Chinese consular agreement that provides for consular attendance at trials prevails over domestic law and must be honoured. Yet the US was refused consular access to Xue's trial under such an agreement, as was Australia during Hu's trial, although other consular access was granted. An official explained that judicial sovereignty took precedence over binding international agreements. There is no question it may be necessary at times to close state secrets trials to protect national security. But a judge should decide that in open court on the basis of clear definitions of state secrets. We have seen what can happen otherwise: matters declared state secrets to prevent disclosure of information, charges used to silence critics and restrict free speech, and agreements violated. These cases are a reminder that people on the mainland are denied information, transparency and accountability other countries take for granted.