In other legal protection (that is non-patent) they've sued everyone from the US Government (over their supposed favouring of Microsoft), Microsoft over the default search engine in IE 7, Froogle over trademark infringement as well as a whole bunch of counter suits.
If I go past the first five pages (which are dominated by Lodsys and Oracle limiting the space for other stories) who knows what else but I really don't have time.
Google are a big company, they have legal muscle and use it, please don't kid yourself it's otherwise.