Chat Restrictions are the first and second tier punishments in the Instant Feedback System. They consist in limiting the player’s chatting ability to a maximum of 5 in-game messages, while pre- and post-game chats are still unrestricted.
Chat Restrictions don’t affect the ability to use pings.
Chat Restrictions are, in fact, intended to make the player consider whether to use their chatting ability to communicate with their teammates in order to win the game, or to keep being a jerk to them. [84, 245]
In short, the main goal of Chat Restrictions is to encourage moderately or occasionally toxic players to reform and shield players from negative experiences, all while retaining their ability to play the game. [130, 217]
The offending player gets restricted within 15 minutes since the end of the match that triggered the punishment, so that the delay between action and consequences is reduced.  Direct feedback is provided in the form of a Reform Card containing from one to three chat logs and in the client, so that players may receive the information they need to understand what they got punished for .
The punishments may escalated quickly in case reform isn’t accomplished.  Serious offenses, such as racist, sexist or homophobic remarks or death threats may skip the Chat Restrictions stage and result in a direct 14 day or permanet ban. [131, 344]
Chat Restrictions are never handed out after a single game nor because of premade reports; the system checks for behaviour patterns in multiple games and punishes according to frequency of misbehaviour , and mostly as a punishment for moderate toxicity.  Before the introduction of time bans, the system used to hand out multiple sets of Chat Restrictions; however, after the implementation of the Instant Feedback System, players with over 1000 restrictions were at risk of being banned if they failed to reform in a timely fashion. 
The Instant Feedback system’s implementation during summer 2015 resulted in a complete wipe of Chat and Ranked Restrictions for all involved players.  The report feedback currently appear only for time bans due to part of the playerbase (about 20% of the surveyed players ) showing no interest in receiving them, while some others were overly interested [58, 127, 374]. During the development of this feature, the report feedback pop-up was set to only appear to the player whose report triggered the punishment, specifically due to the concerns about spamming too many pop-ups. 
The intention behind punishments is to deal them only when there’s the absolute certainty that a punishable offense occurred. 
Chat restrictions are not given "on demand" since past experiments have shown that players who request a chat restriction do not reform but instead use their remaining messages to stay very toxic .
Due to human bias, it may seem that chat restricted players numbers are very high, but they’re actually much less than players with ribbons. 
75% of the players afflicted by Chat Restrictions improve their behaviour afterwards.  The reason the system doesn’t issue more Chat Restrictions after the initial two waves lies in the fact that reform rates plummet after the first punishment, so Riot saw no point in implementing more steps between restrictions and bans. 
Before the implementation of the Reform Cards, the percentage of players improving their communication was set at 71% [161, 246], which resulted in an estimation that Chat Restrictions are 4% more effective compared to bans.  The combination of Chat Restrictions and time ban punishments has resulted in 40% more players reforming, compared to the old ban system. [220, 461] Furthermore, the Instant Feedback System has seen an increase of reform rates at 91,6% compared to the previous system. 
Many Chat Restricted players have noticed that using chat positively has impacted their win rates.  It was also found out that being restricted didn’t hinder the player’s team at all, if smart pings were used intelligently , except for the jungler who had some difficulty. These tests resulted in the choice of giving 10 and 25 Chat Restrictions specifically. 
Fewer than 1% of players have received any form of punishment. [189, 198, 199] Adding to this, according to statistics from 2014, 95% of active players have never received a punishment of any kind. [190, 198]
False positive rates lie around less than 1% of the punishments being given. 
Chat Restrictions decreased reports against Chat Restricted players by 20%. 
Many studios and game developers have begun following Riot’s footsteps in implementing systems similar to the Chat Restriction system. 
127 https://ask.fm/RiotLyte/answers/130577014978 ; Page 322
161 http://gdcvault.com/play/1020389/Enhancing-Sportsmanship-in-Online [28:06]
162 http://gdcvault.com/play/1020389/Enhancing-Sportsmanship-in-Online [28:06[
170 https://ask.fm/RiotLyte/answers/130580680386 ; Page 319
310 https://ask.fm/RiotLyte/answers/130593104322 ; Page 309
329 https://ask.fm/RiotLyte/answers/133550867394 ; Page 57
364 https://ask.fm/RiotLyte/answers/132088444610 ; Page 133
374 https://ask.fm/RiotLyte/answers/131060874178 ; Page 207
381 https://ask.fm/RiotLyte/answers/131034044610 ; Page 215
388 https://ask.fm/RiotLyte/answers/130717991362 ; Page 282
410 https://ask.fm/RiotLyte/answers/130752309954 ; Page 267
459 https://ask.fm/RiotLyte/answers/132459485122 ; Page 103
461 https://ask.fm/RiotLyte/answers/132353661890 ; Page 108