We do not write because we want to; we write because we have to - Somerset Maugham
The government wants to know, specifically, how often pornography or pornographic terms are searched for on the site.
Alberto Gonzales, in his official capacity as attorney general, filed suit in a San Jose court on the 18th of January to compel compliance with a subpoena.
But Google, according to the San Jose Mercury News, opposes releasing this kind of information to the government. A federal court in Pennsylvania is currently deliberating over the provisions of the contested 1998 Child Online Protection Act.