Confused about this whole NBA coach's challenge thing? We're here to help.
Following in the footsteps of the NFL and MLB, the NBA introduced a coach's challenge for the 2019-20 season. The tool used by coaches to trigger replay reviews was previously tested out in the G League, and the NBA Board of Governors decided to implement a version of the challenge for at least one year.
This doesn't mean coaches will be stopping the officiating crew for an argument over every call, though. Coaches are limited in what they are able to challenge, and referees will continue to play a major role in what is reviewed during crucial late-game possessions.
How the NBA coach's challenge works
• Each team has one challenge available per game. The NBA doesn't reward coaches for successful challenges unlike the NFL and MLB. It's one-and-done, regardless of the result.
• In order to initiate a challenge, a coach must call a timeout and then ask for a replay review prior to the start of a free throw attempt, change of possession or jump ball. During games, you may see the standard spinning motion with an index finger used as a signal from coaches to trigger a review as well as flashing lights at the scorer's table.
• If a challenge is successful, the team keeps its timeout. If the call on the floor stands, that timeout is gone.
• A coach can challenge these types of plays:
Personal foul calls made against his team at any time
Out-of-bounds calls during the first 46 minutes of regulation and first three minutes of overtime
Goaltending/basket interference calls during the first 46 minutes of regulation and first three minutes of overtime
• During the last two minutes of the fourth quarter and the last two minutes of an overtime period, reviews of both out-of-bounds and goaltending/basket interference calls can't be challenged by coaches. Reviews can only be triggered by referees.
• A key point: coaches can't challenge non-calls. That means a coach is only able to force a review of a foul called on the floor that he believes is not a foul. A coach can't challenge a call that was missed in order to change it to a foul. However, other reviewable issues can be covered as part of the challenge (foul called on correct player, continuation, out-of-bounds, etc.).
• The on-court crew chief makes the final decisions on foul call reviews. The replay center referee makes the final decisions on all other reviews.
• Here is the wording that matters most on challenges: "clear and conclusive evidence" is required in order to overturn a call on the floor.
• NBA vice president of replay operations Jason Phillips provides a few examples below of plays that could be successfully challenged under the new rule.