If you've ever played Rainbow Six: Siege, you'll know a rampant problem in the game is griefing in the form of friendly-fire. Sometimes you'll be queued up with people who take the game a little more seriously than others, and if you make a simple mistake like accidentally reinforcing the wrong wall, they'll take a few shots at you with their gun, or maybe jump right to the killing you part. Either way it gets very annoying and tedious to deal with. Of course, sometimes accidents happen, but in the Siege community, this is a well known form of griefing and grows more rampant as the days go by.
But thankfully Ubisoft has heard the cries of it's fan-base, and is rolling out a new in-game feature: Reverse Friendly-Fire (RFF). With this new feature, if a toxic teammate kills you, the RFF activates and will allow the downed teammate to either confirm if it was done with toxic intent, or accidentally. If you confirm that is was done intentionally, then any further damage done to you is reflected to the other players. Thus the term, Reverse Friendly-Fire.
Hopefully this new system will stop the team-killings from being as rampant as they currently are. While it probably won't completely remove the form of griefing from the game, it may certainly help in cutting it down. Ubisoft has also stated that this won't be the final version of the RFF system, and they will adapt and change it as the community gives feedback. But this could be a very good and useful tool for future games.
We will just have to wait and see.