The Chinese government is strict concerning adherence to its laws and regulations. If a foreign teacher breaks Chinese laws, they are subject to Chinese punishment, incarceration, and/or deportation, depending on the infraction. In most cases, embassies are powerless to help the teacher in trouble other than notify family and act as consultant. Breaking Chinese regulations can be as small as not having your Residency Permit in a timely manner (fine is involved) to being involved in a traffic accident where the blame is put on the foreigner. The foreign teachers should realize that any infraction in their own country is probably an infraction in China.
Foreigners should not participate in any political gatherings and should be aware that underground churches are monitored. Participation can be perceived as breaking the law and arrest can follow. Proselytizing is also not allowed, in or out of the classroom.
There are now many law firms in China who have American-trained lawyers on their staffs.