As with similar lawsuits, the crux of the issue is Riot’s assertion that the software violates copyright by reverse-engineering the copyrighted game code. While the company initially sought to settle the matter out of court, it is further alleged that LeagueSharp was unresponsive, this requiring further litigation. There are also allegations regarding a Riot employee whose personal information was leaked by LeagueSharp, which is a rather serious accusation. It remains to be seen how these accusations will play out when put up to the scrutiny of the legal system.
Source: Kotaku