Not paying the wages of farmers-turned-workers on time has become a chronic problem. So severe is the problem that in 2003, Premier Wen Jiabao intervened personally to get a migrant worker her arrear wages.

The central and local government have indeed taken measures to solve the problem. But there is no denying that it is becoming more complicated by the day.

From 2006 to 2010, the total arrears due to migrant workers decreased. In February 2011, China's top legislative body adopted the amendment to the criminal law, which was aimed at making deliberate defaulting on wages a crime. But the number of such cases in 2012 increased from the year before.

Last year, labor security and supervisory departments across the country handled 218,000 such cases, up 7.5 percent year-on-year. The number of unrests involving 100 or more migrant workers denied their wages reached 190 between January and November in 2012. And the amount the labor security and supervisory departments realized for 6.225 million migrant workers totaled 20.08 billion yuan ($3.23 billion) in 2012, testifying to not just what the government has done in this regard, but to the severity of the problem.

Incidentally, the increase in such cases last year coincided with the increase in local governments' investments in construction projects, which reached 7 trillion yuan late last year.

There is no evidence to suggest that there is a connection between an upsurge in local investment and the rapid increase in the number of wage-default cases as well as the amount involved. But that the majority of cases took place in the real estate sector seems to support my assumption that there indeed is a connection between the two.

If a construction project has enough funds, there is no reason for the employer to default on his/her workers' wages, unless he/she wants to keep the money for other purposes or intends to flee with it. The problem arises when a construction project is sub-contracted down the line and every sub-contractor wants to make easy money by sub-contracting the project to another. In such a case, a sub-contractor may not have the money to pay his/her workers before being paid for the work he/she has contracted.

Whatever the reason, the government has to crack down on employers defaulting on wages not just for social stability, but also to protect the rights and livelihood of the most disadvantaged group in the country.

Only 120 offenders have been tried for defaulting on their employees' wages in the year and half since the criminal law amendment took effect. But sometimes it is not easy for a court to find out whether an employer intended not to pay workers' wages in time despite having enough funds. And even if an employer is tried in court and found guilty, it does not necessarily mean that the workers will get their arrear wages. That explains why not many migrant workers appeal to a court when they don't get paid on time.