Oracle , claiming the Google-backed Android OS violated a number of Oracle-held Java patents and copyrights.

Google's request that the USPTO take a second look at the validity of a number of the contested patents is not an unusual move: some 780 requests for ex parte re-examinations were filed last fiscal year, and more than 180 have been submitted so far this fiscal year, according to a Dec. 31 . Nearly all, 92 percent, of the 11,211 filed since 1981 have been granted, the document shows.

In 23 percent of the cases, the patents were upheld as is, according to the document. Twelve percent were thrown out. But 65 percent have been subject to some type of change, it states.

It's not clear when the USPTO will complete its review of the Oracle patents, should one be granted, but it likely wouldn't be anytime soon.

While the USPTO document says patent re-examinations on average take about 26 months, "everyone doubts those statistics," said Scott Daniels of the Washington, D.C., law firm Westerman, Hattori, Daniels and Adrian. Daniels was the first to report Google's USPTO filings, in a on Wednesday.