These days, you probably cannot see a single NBA game without seeing the referees at least checking a few calls or actions via instant replay. For example, when two players are in an altercation and it has to be decided whether they have to receive a technical foul or that they might even have to be ejected. But, the reds are only allowed to do so on the basis of strict guidelines. Sometimes, it seems like the use of instant replay would definitely be necessary, for example if it is not clear who let the ball go out of bounds, but then it is not allowed. The question is when the referees can make use of the technology.
The instant replay was first used in the NBA in the 2002-2003 season. Through the technology, the refs could decide whether a score counted or that the clock had already expired. It took five more seasons to implement the fact that the instant replay could be used for a lot more moments during the game. It was decided that the instant replay could also be used to determine if players had to be ejected from the game after a fight or a flagrant foul had to be given out. Thereafter, the replay could be used to make sure a score was worth two or three points. Last, in the 2013-2014 season, off-ball- and (possible) flagrant fouls could also be reviewed with instant replay.
Now, there are 15 instances the referees can use the technology as a supporting system for their calls: 1. A last second field goal 2. Last second foul 3. Review of called foul 4. Player altercation 5. Clock malfunction 6. Two-point/three-point field goal 7. Out-of-bounds play 8. Shot clock violation 9. Clear-path-to-the-basket-foul 10. Correct free throw shooter 11. 24-second shot clock reset 12. Restricted area block/foul 13. Goaltending 14. Off-ball foul timing 15. Number of players on the court.
As you can see above, there are a lot of moments the instant replay can be used. Therefore, since 2014-2015 season, there is also a special ‘Replay Center’ in New Jersey that has access to cameras from a lot of different views to review a situation. This is to make sure the right decision is taken and the game is not delayed too much.