FILE - In this May 11, 2014, file photo, NBA Commissioner Adam Silver, center, talks with Magic Johnson, right, as Kiki Vandeweghe looks on as they watch the Los Angeles Clippers play the Oklahoma City Thunder in the first half of Game 4 of the Western Conference semifinal NBA basketball playoff series, in Los Angeles. The NBA will experiment with a coaches' challenge for summer league games, one where teams will have the ability to seek a review of certain calls in the final 2 minutes of regulation and overtime. Coaches will have to call a time-out before live play resumes, and then trigger a blinking light on the scorer's table to initiate the challenge. "We're going to try it in limited form," NBA executive vice president for basketball operations Kiki Vandeweghe said.(AP Photo/Mark J. Terrill, FIle)