RESEARCH TRIANGLE PARK, N.C. – PC makers who are relenting to Chinese government demands that they install web filtering software on computers sold in that country may now face another challenge – a legal one.

Solid Oak Software told PC World on Thursday that it plans to sue Morrisville-based Lenovo along with Acer and Sony for installing the so-called Green Dam software from a Chinese firm, Solid Oak claims its code was stolen for use in Green Dam.

In a study of Green Dam, University of Michigan researchers reported: “Some of the blacklists appear to have been copied from American-made filtering software.” Read more about the study

The companies did not respond to for comment.

Lenovo confirmed in a statement to Local Tech Wire and on Wednesday that it would in fact install Green Dam or ship it as a CD. Other companies have also said they would comply with China’s demand, although the government has put the mandate on hold after internal and global protests about the decision.

Green Dam is supposed to filter content the Chinese government has determined to be pornographic and political.

U.S. PC makers Hewlett-Packard and Dell have yet to announce their plans. HP is the world’s No. 1 PC manufacturer followed by Dell, Acer and Lenovo.

top product is called CyberSitter. The California-based firm has been quite vocal in its claims about Green Dam and last week reported to the FBI that it had been the victim of a cyber attack, apparently from China.