Any time Nintendo has a successful system, this happens- they end up being sued by someone who claims that Nintendo has stolen their idea. This happened with the Wii. It happened with the 3DS. And now, it is happening with the Switch.
Gamevice is a company that has made the Wikipad, as well as a line of snap-on controllers for mobile devices. It is also a company that has already sued Nintendo for infringing on its patents with the Switch. Nintendo won that suit, but now, the US International Trade Commission has begun investigating Nintendo and Gamevice’s complaints. The USITC does note that while it is investigating Nintendo, this should not be taken as evidence that Nintendo is guilty (or not guilty). For now, the Commission will hold an evidentiary hearing. The USITC will announce a target date for the end of the investigation within 45 days, and a final decision will be made as soon as is possible.
So- the fate of the Switch (technically) hangs in balance, if Nintendo is found guilty. On the other hand, should that happen, Nintendo will probably end up settling with Gamevice anyway.