Google has formally rejected a demand from the US government to hand over a week's worth of search records.
Google's stance in China has led to widespread criticism
The rejection was made in court documents Google filed in response to official demands for search data.
In the strongly-worded papers Google said the request would violate the privacy of its users and reveal trade secrets to its rivals.
It also added that handing over the data was impractical and would not accomplish what the government wanted.
The US Department of Justice (DoJ) made the request for a week's worth of search records in late January. It made similar requests of other big net firms such as Microsoft, Yahoo and AOL.
Initially, Google resisted the request from the DoJ and in court documents filed over the weekend has formally rejected it. The 25 page document uses strong language to criticise the request for a list of the search terms used in a typical week.
The DoJ has made the request to shore up attempts to show that voluntary regulation is not doing a good enough job of keeping children free of the unsavoury material, largely pornographic, that exists online.
The document expressed its disbelief in US goverment assertions that the list of search words would help understand user behaviour.
"This statement is so uninformed as to be nonsensical," comments the document.
Google said the government request was flawed because it constantly tuned the algorithms behind the index that returns particular sites for particular search terms.
This tinkering means that results for one search may not be the same from week to week.
China's growing ranks of net users are proving a strong lure
Google also said that it would take more than a week of work by one of its engineers to compile the list.
The documents go on to say: "Google users trust that when they enter a search query into a Google search box ... that Google will keep private whatever information users communicate absent a compelling reason."
The American Civil Liberties Union also filed court documents supporting Google's stance.
Lawyers for the ACLU wrote: "This subpoena is the latest example of government overreaching, in which the government apparently believes it can demand that private entities turn over all sorts of information about their customers just because the government asserts that it needs the information."
A court hearing to decide the row is scheduled for 13 March.
Despite its stand against the DoJ demands for search data, Google has been heavily criticised in recent weeks for its stance in China where it is co-operating with the regime's demands for control of the net.
In early February at a US Congressional hearing Microsoft, Yahoo, Cisco Systems and Google all faced strong criticism over how they conducted themselves in China.