Coaches of NBA teams will receive a new right in the the 2019 Summer League – according to a memo sent to teams and obtained by ESPN, coaches will get one challenge per game for asking the referees to review their decision in the game. The new rule is expected to be also implemented in the 2019-20 season.

The challenge can be used on called fouls, goaltending, basket interference and plays when the ball is knocked out of bounds, according to the memo. Moreover, whether the challenge turns successful or not, coaches only have one chance. The NBA already tested the effects of such system in the G League in the past two seasons.

If a coach wants to use the challenge, they will first need to call a timeout and do it right after the moment he wants to challenge happens. Then the coach must "twirl his/her index finger toward the referees" as a signal for using the challenge. If the challenge is successful, the timeout called will be recovered; if the challenge is not successful, then the team will that timeout.

The outcome of challenges against fouled calls will be decided by the crew chief among the referees while the NBA Replay Center in New Jersey will determine the others. Furthermore, all technical or flagrant fouls happen during or immediately after the challenged moment will stand, regardless of the result of the challenge.

One more thing about the new rule is that coaches cannot challenge uncalled fouls. The memo said the challenge will be part of a one-year pilot program in the next season.

The conflicts between players and referees in the NBA have been growing fast in recent years. For players, sometimes one simple call by the referees can determine the result of a game; for referees, they have to make judgment over things that happen too fast for their eyes to catch. The new challenging rule seems to be towards players but it also comes with risks. Think about it, when you challenge in the last possession of the game and fail, you also lose a precious timeout.