That’s exactly what’s being tested right now on the North American servers. The new system will receive player reports of bad behavior, attempt to verify the offense, and deliver an appropriate punishment (temporary or permanent bans) within minutes of the submission.
“When negative behavior occurs, we know that the faster a player receives feedback, the better their chances of reforming,” Riot Games reasoned. The studio said that it will have a team to monitor the first few thousand cases and has plans to expand the system to include positive rewards in the future as well as follow-up notifications to those affected.
Source: League of Legends via Gamasutra