Why does China punish foreigners for taking drugs in other places (even where it’s legal)?

China’s strict drug laws have led to a senior executive from German car giant Volkswagen being kicked out of the country soon after returning from a holiday in Thailand.

The foreign ministry has confirmed that Jochen Sengpiehl, VW’s chief marketing officer and head of product strategy for China, had tested positive for cocaine and been detained for 10 days before his expulsion.

Media reports have said he also tested positive for cannabis, which is legal in Thailand although cocaine is not.

The case serves as a reminder of Beijing’s “zero-tolerance” approach to drugs, and the risk that foreigners can be detained for drug use outside the country. Here is how the law operates.

Can travellers be tested when entering the country?

Yes. Random drugs tests may be carried out on flights from places where cannabis and other drugs have been decriminalised, with students and foreigners likely to be targeted.