It's likely NBA coaches will be challenging one call per game next season.
The league told teams Friday that, pending expected approval by the Board of Governors on July 9, coaches may challenge a personal foul charged to their team, a called out-of-bounds violation, a goaltending violation or a basket-interference violation. No other call may be challenged.
"We anticipate this rule will be in effect in the NBA next season as a one-year pilot program," NBA Basketball Operations President Byron Spruell told teams in the memo, a copy of which was obtained by The Associated Press. ESPN first reported the memo's contents.
The NBA already has a call-challenge program in place in the G League and tinkered with it during summer league last year. It will be used during all three Summer Leagues this season -- the four-team league in Sacramento and Salt Lake City that open Monday, and the one in Las Vegas that opens July 5.
Unlike the NFL version of a challenge, there's no flag to be used and teams will not retain them even if successful. A team will have to call timeout and the coach "must immediately signal for a challenge by twirling his/her index finger toward the referees," the memo said.
A challenge must come immediately after the play and challenges of out-of-bounds calls, goaltending or basket interference will not be permitted in the last two minutes of the fourth quarter or the last two minutes of overtime.
"As with other replay reviews, in order to overturn the event as called on the floor, there must be clear and conclusive visual evidence that the call was incorrect," the memo said.
If the challenge is unsuccessful, the team will lose its timeout. If the challenge is upheld, no timeout will be charged.
Also likely coming to the league: Instant replay can be triggered by officials in the review center in Secaucus, New Jersey, without the involvement of the on-court crew.
The league said it wants to give the replay center the authority to review whether a shot was a 2-pointer or 3-pointer without on-court crews asking for it, as well as the ability to review potential shot-clock violations. A courtside administrator would be added to the crew at the scorer's table to communicate with the replay center and then be the liaison to announce any immediate scoring changes.
For Summer League only, there will be a "transition take foul" -- one free throw and retention of the ball when a defender commits a take foul against any offensive player during a transition scoring opportunity but does not meet the criteria of a clear-path foul.
And in Las Vegas, a new high-tech element will make its debut.
What the NBA calls a "connected basketball" will sometimes be in use for those games. The NBA said it has been working with Spalding and other vendors to develop a basketball with a tracking chip inside, and prototypes will be tried out during the Vegas league. Some companies have been in the smart-ball game for a few years, offering users the chance to use apps to track their accuracy and other data.