The U.S. Senate plans a March hearing on technology companies' business practices in Internet-restricting countries. Executives from Google and other tech firms, as well as administration officials, are expected to testify about their efforts to promote Internet freedom. The exact date of the hearing has not been set.

As a prologue to the hearing, Sen. Dick Durbin (D-Ill.), the assistant majority leader and chairman of the the Judiciary Subcommittee on Human Rights and the Law, sent Feb. 2 letters to 30 information and communications technology companies, including Apple, Facebook, Skype and Twitter about their human-rights efforts in China.

Durbin’s letter asks each firm for details of its business in China, and what, if any, measures it will implement to ensure that its products and services do not facilitate human rights abuses by the Chinese government.

The hearing was prompted by the recent controversy between Google and China. Google said Jan. 12 it will stop censoring searches on its Google.cn and reconsider the feasibility of even doing business there after the search giant reported cyber-attacks from within China aimed at gaining access to the Gmail accounts of human rights activists. Google also said 20 other companies from a wide range of businesses had suffered similar attacks.

"I commend Google for coming to the conclusion that cooperating with the 'Great Firewall' of China is inconsistent with their human rights responsibilities," Durbin said in a statement. "Google sets a strong example in standing up to the Chinese government’s continued failure to respect the fundamental human rights of free expression and privacy. I look forward to learning more about whether other American companies are willing to follow Google’s lead.”

Durbin's inquiry also follows up on a letter that Durbin sent last year, urging technology firms to join a voluntary code of conduct known as the GNI (Global Network Initiative) The code of conduct, which regulates the actions of technology firms operating in countries that restrict the Internet, has been backed by Google, Microsoft, and Yahoo, although little progress has been made on the initiative.