That was in 2010. When did Google start developing Android? Well, let's see, Andy Rubin & Co. started working outside Google in 2003, then Android gets purchased in 2005, then in 2007, AOSP is made public for the first time, then in 2008, finally, the first Android phone is released. Those events ALL predate Oracle's purchase.
So, with that in mind, Google sure didn't copy Oracle's code, did they? No, they copied Sun's. Which, of course, was ALL open source until Oracle came along and pulled their shenanigans on the open source community with this demon of a purchase. Corporate mergers aside, for SEVEN LONG YEARS, Sun never raised a finger in court. Not until Oracle came and bought them.
According to Article 1, Section 9, of the United States Constitution, "No bill of attainder or ex post facto law should be passed." Right there, retroactively suing someone after seven years of free will, of perfect harmony and cooperation between parties, is exactly what Oracle is doing. Yeah, let's see what the Supreme Court has to say about this, shall we?
Given that copyright and patent infringement are both crimes that Oracle is retroactively accusing Google of, the Cadre v. Bull decision shouldn't apply here either, because again, they have a basis in criminal law, which is why music, video, and software "pirates" are manhunted and sent to jail so often by police and media outlets. This is no different than that... So yeah, let's all make sure the Supreme Court hears our cries (and this case), because the ex post facto clause is exactly what gave Google the initial victory in the first place.