What have you searched for today? This week? This year? Some law enforcement agency somewhere may love to know.

On Tuesday, the American Civil Liberties Union announced that it had filed a formal request (PDF) under the Freedom of Information Act (FOIA), asking various federal judicial agencies what “policies, procedures, and practices [are] followed to obtain search queries from search engine operators for law enforcement purposes.” The ACLU also asked if a warrant or another legal process is required to make requests and if requests can be intercepted in real time.

Specifically, the FOIA request applies to a number of federal agencies, including the United States Department of Justice, the FBI, the Drug Enforcement Administration, the Office of Legal Counsel, and the executive offices of a number of United States Attorneys, including those in California, Massachusetts, Texas, and other places.

The ACLU wrote on its blog:

There are two kinds of information law enforcement might seek from a search engine: records of search queries entered by a particular person or persons; and a list of the names, IP addresses, or other identifying information for some or all people who have entered a particular query into the search engine’s webpage. Representatives of the two largest search engines, Google and Bing, have suggested that they think the government needs a warrant to get this information. But we don’t know what the government’s policies are, nor how the search engines have reacted when presented with a government request for users’ search query data.

Ars has profiled two search engines that claim to not log any IP addresses: DuckDuckGo and Ixquick. While they earn revenue, those search engines only constitute a tiny portion of search traffic in the United States.

“Not really knowing about [what the other guys do], we independently made the decision that we wanted to go down this route of not storing this data,” explained Gabriel Weinberg, DuckDuckGo's founder, in an interview with Ars in 2012.

“Search engines have a history of getting subpoenas, and Google has been more and more open to the requests that they were responding to," he added. "It seemed inevitable that search engines would get requests from law enforcement—I don’t like that idea of handing over data.”