Oracle sued Google in August over a number of alleged Java patent and copyright violations in Android.

"Any use in the Android Platform of any protected elements of the works that are the subject of the Asserted Copyrights was made by third parties without the knowledge of Google, and Google is not liable for such use," Google attorneys wrote in one of 20 defenses to Oracle's amended complaint.

Another defense states that Android was "created independently and without reference to any works protected by the Asserted Copyrights."

Elsewhere in the document, Google discusses the formation of the Open Handset Alliance, the coalition of vendors, including Google, that worked together to develop Android.

The filing also notes that Android can be freely downloaded and developers are free to modify the source code to suit their needs.