Major League Soccer announced on Monday that the league will be working with the Professional Referee Organization (PRO) and the United Soccer League (USL) on live in-game Video Assistant Referee (VAR) testing in 25 matches during the 2017 USL season which kicks off on Saturday, March 25 (full schedule follows below).

The Video Assistant Referee (VAR) initiative consists of an additional referee positioned in a booth with video technology that allows access to every available broadcast camera angle at a finger's touch. A communication system allows the VAR in the booth to alert and advise the head referee of clear errors in four types of game-changing situations: goals, penalty decisions, direct red card incidents and cases of mistaken identity.

MLS has been at the forefront of VAR testing in conjunction with the International Football Association Board (IFAB), the world body that oversees the Laws of the Game of soccer. MLS and USL partnered to host the world's first competitive matches featuring in-game VAR testing in August 2016 and that was followed by the first MLS exhibition matches featuring live VAR experiments during the 2017 preseason.

The 2017 MLS season will see the league run offline testing (no impact on matches and no direct communication with referees) at all 22 venues through the 2017 MLS All-Star Game presented by Target, after which the league hopes to formally incorporate VARs in select official MLS matches.