Google claimed that Sonos infringed on a collection of patents related to voice recognition and voice control:

"Google has patented inventions on innovative technologies for enabling voice assistant technology and providing improvements to the efficiency, reliability, and durability of voice-controlled and battery-powered devices. Sonos is using, without permission, these technologies in its products to enable multiple commercially-desirable features."

Google points out the new Sonos Voice Control feature that was just launched in June, which allows some of the company's best speakers to listen for a "hotword" to quickly and "efficiently" respond to a user's command. Google says that Sonos is not licensed to use the search giant's intellectual property for this purpose. It also alleges that products like the portable Sonos Roam infringe on its wireless charging technology.

Google claims that Sonos has "started an aggressive and misleading campaign against our products, at the expense of our shared customers."

But this is really about the ongoing patent dispute between the companies, which came to a head earlier this year when Sonos was granted an injunction against several Google products infringing on its patents. This forced Google made several changes to how its smart speakers handle audio or face an import ban.

Rather than paying Sonos, or even being nice about it, Google has just thought about tit for tat reprisals because nothing is better PR than huge multi-nationals picking on smaller companies.  

Google says it plans to file with the US International Trade Commission in an attempt to have an import ban placed on Sonos products.

Sonos Chief Legal Officer Eddie Lazarus issued a statement suggesting that Google's lawsuit would get it nowhere.

"Google previously sued us all over the world and Sonos has prevailed in every decided case. By contrast, the courts have repeatedly validated Sonos' claims that Google is infringing its core patented smart speaker technology. Google's new lawsuits are an intimidation tactic designed to retaliate against Sonos for speaking out against Google's monopolistic practices, avoid paying Sonos a fair royalty for the roughly 200 patents it is currently infringing, and grind down a smaller competitor whose innovations it has misappropriated. It will not succeed."