On landing at Los Angeles airport on May 15, Zhang Hao, a professor at Tianjin University, was arrested by US police for suspected economic espionage. Five of his colleagues and some of his students, believed to be in China now, too have been indicted by the US for "stealing sensitive American technology" for smartphones and potential military applications.

Zhang and some of the other accused studied and worked in the US for a few years, during which they might have developed some acoustic technologies for mobile phones for their companies. They returned to China in 2009 and continued working in the same field - research and development in and manufacturing of semiconductor chips - which made them vulnerable to legal issues.

The possible problems they faced while doing so included: Would the technologies they developed in the US be the properties of their previous employers? Did they bring to China other technologies that were solely owned by the US entities? If yes, did they settle with the US entities how to use them without legal complications? Would the new technologies they developed after returning to China be subject to legal limitations which they might still be under because of their R&D work in the US?

Given the increasing number of Chinese returning home from abroad, such legal issues are bound to be on the rise. Such problems have to be properly tackled by China and the US to protect each other's legitimate intellectual property rights (IPRs). And Zhang's case should be a warning to people with a similar background - having studied and worked in the US before returning to China - to be cautious about using American technology for free.

But this doesn't justify the way Zhang and his colleagues have been treated by the Barack Obama administration. Faced with increasing number of cases involving US trade secrets, Washington should first establish bilateral collaboration with other countries to crack down on illegal use of technologies developed in the US, or visa versa. Short of this, it is highly improper to invite some "suspects" to the US to attend special programs and detain or arrest them for violation of IPRs.